Grade Level

Worms!

Thursday September 29, 2011

Here we’re going to discuss the differences between three types of worms; flatworms, roundworms, and segmented worms. The word “worm” is not, in fact, a scientific name. It’s an informal way of classifying animals with long bodies and no appendages (no including snakes). They are bilaterally symmetrical (the right and left sides mirror each other). Worms live in salt and fresh water, on land, and inside other organisms as parasites.

The differences between the three types of worms we will discuss depend on the possession of a body cavity and segments. Flatworms have neither a body cavity nor segments. Roundworms only have a body cavity, and segmented worms have both a body cavity and segments.

Flatworms (Phylum Platyhelminthes) have incomplete digestive systems. That means that their digestive system has only one opening. The gas exchange occurs on the surface of their bodies. There are no blood vessels or nervous systems in flatworms. Some are non-parasitic, like the Sea flat worm, and some are parasitic, like the tapeworm.

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Roundworms (Phylum Nematoda) have body cavities—as contrasted with flatworms which do not. The body cavity allows roundworms to have complete digestive tracts (both a mouth and an anus). The mouth and anus are connected by a gut—where the food is digested. They also have a simple nervous system and brain.
Roundworms can be parasites of plants and animals. In dogs they are often know to cause heart problems. In humans roundworm parasites can sometimes cause a swelling disease called elephantitis.

Annelids or Segmented Worms (Phylum Annalida) the most developed of the three, have both a body cavity and segments. Their body cavity helps give them structure—it serves as a hydroskeleton. By “segmented” it’s meant that they are divided into repeating units. They can be non-parasitic (i.e. earthworms) or parasitic (i.e. leeches). Interestingly, the giant red leech only eats giant earthworms.

Worm Column

If you’re fascinated by worms but frustrated that you can’t see them do their work underground, then this worm column is just the ticket for you. By using scrap materials from the recycling bin, you’ll be able to create a transparent worm farm. here’s what you need:

two 2-liter soda bottles, empty and clean
one brown paper grocery bag
20 red worms
newspaper, old leaves, peat moss, and/or straw for worm bedding
last night’s dinner, organic scraps, plant material for worm food

Here’s what you do:

Download Student Worksheet & Exercises

Things to Compare with your Worms:

Look at the worms under the magnifying glass.
Measure the lengths of the worms.
Make note of:
1. The outer layer of the worms: Is it hard? Is it segmented? What are other observations that can be made?
2. Do they have legs?
3. Do they have antenna?
4. What are the main differences?
5. What are the main similarities?

Garden Worm Tower

Here’s how you can make your own worm tower right in your garden:

Build your own worm farm and watch them turn food scraps into soil!

Materials:

2 polystyrene boxes with lids the same size. (Let’s call them Bin A and Bin B.)
A sheet of insect screen to fit the bottom of the boxes
Newspaper clippings
Garden soil
Food scraps (half-eaten fruits and veggies, stale biscuits and cakes, crushed egg shells, coffee grounds)
Water
Worms (Either “Tiger”, “reds”, or “blues”; ask for them at your local garden store)

Build the farm:

Punch evenly spaced holes in the bottom of Bin A.
Place the insect screen on the bottom of Bin A (this is so that the worms don’t fall out).
Fill Bin A ¾ full with wet newspaper clippings.
Add a layer of garden soil to Bin A.
Add the worms.
Place Bin A in Bin B. Make sure there’s enough room in Bin B when Bin A’s placed in it to collect the worm pee and waste. Be sure to empty and clean Bin B every couple days.
Add food to bin A! Start off small. You don’t want to over-feed the worms. Start out with a couple scraps in the corner and see how long it takes for them to disappear—that should give you a good idea of how much to feed your worms.

Earthworm Dissection

You can dissect a earthworm right at home using this inexpensive earthworm specimen and simple dissection tools!

Exercises

What are three types of worms?
What are the characteristics of each?
What are the elements of a complete digestive system?
What are some benefits of worms in gardening?

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Butterfly Life Cycle

Wednesday September 28, 2011

Insects are not only the most diverse subgroup of arthropods, but with over a million discovered species it is the most diverse group of animals on earth. Although they can’t all be as beautiful as a butterfly, they all play important roles in their ecosystems—just think of where we would be without bees!

The segmented exoskeletons of insects have a hard, inner layer called the cuticle, and a water-resistant outside layer called the exocuticle. Insects are divided into two major groups: winged insects and wingless insects. Air is taken in through structures called spirials, and delivered directly to the body.

Most insects reproduce sexually and are oviparous (hatch from eggs after the eggs are laid), although some insects reproduce asexually.

You can grow your own butterflies using a premade kit from Home Training Tools!

Biological Nets

Wednesday September 21, 2011

A biological net is one of the essential tools of a field biology researcher — you! A bio-net allows you to safely and gently gather samples. Whether you’re studying butterflies or tadpoles a bio-net is the tool to have! Important safety note: Do both of these with parental supervision. Many of the steps are tricky and involve sharp objects.

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What you need (these materials are not listed int he main shopping list, as this project is a little more involved):

1-meter x 2-meter fly-wire screen netting (gauge = 0.6mm spaces)
4 strips (20cm x 1m) of heavy canvas
2 broom handles
Nails
Thread
Hammer
Sewing machine
Ironing board with iron

How to make a two-handled bio-net:

Basically, you’re going to create a square net of fly-wire, frame it with the strips of canvas, then attach the broom handles to either side. Your final product should look like this:

Fold the fly-wire in half so it’s 1m X 1m.
Fold the edges of the canvas strips under so there’s a smooth edge to each of the sides of the strips. About 1cm each side should work.
Sew two of the strips to the top and bottom of the fly-wire square.
Sew the other two to the sides of the fly-wire, but leave enough space for the broom handles to slip in.
Slip the broom handles into the sleeves you just created. Use the nails to firmly attach the canvas sleeves to the handles. These are the handles of the bio-net. Voilà!

How to make a single handled sampling net:

What you need:

4 (60cm X 30cm) pieces of fly-wire netting (250um mesh)
1.5m piece of bias tape
1m (or longer) broom handle
Thread
Scissors
Sewing machine
3 wire coat hangers
Drill with 0.5com wood bit
Pliers
Binding

Let’s make the net!

Cut the netting into four triangles (50cm high with 30cm bases) (1).
Sew them together into a single net.
Sew a 1.5m strip of bias tape onto the net. Don’t sew both sides. Leave the outside flap un-sewn so that you can sip the wire in (2).
Drill a hole in one of the ends of the broom handle.
Remove the hooks from the hangers.
Untwist the hangers and slip into the bias-tape sleeve.
Sew the bias tape sleeve closed.
Twist the tops of the hangers together into a stem and insert into the hole in the broom handle.
Bend the hanger hooks into a “U” and use it to bind the net to the handle.
Bind the U to the broom with the binding (5).

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Raising Orange Spotted Roaches

Thursday September 1, 2011

When you hear “roach” you might not immediately think of something that would make a good pet, but not all roaches are like the cockroaches you might have seen in your house!

Species such as the Orange Spotted Roach (Blaptica dubia) make excellent insect pets: they don’t cost much, they have an interesting life cycle and habits, and they do not require much effort to care for. Their average lifespan is about 18 months and you’ll be able to learn more about their fascinating life cycle (from egg to adult) if you allow them to breed!

A pet roach isn’t a pest?

It may seem like all roaches are pests, but of 4,000 species, only 4 or 5 live in homes and are considered pests (such as the American cockroach). Most roaches live in tropical environments far from domesticated areas. They are very different from the kind of household pest you might think of when you hear “roach.”

You might think roaches would make pretty boring pets, but they are surprisingly fast and fun to watch. You can learn a lot about insect anatomy and what makes roaches unique by taking care of them. The species that make good pets do not smell, are not noisy, cannot fly, and generally are very easy to clean up after. They typically are most active at night, because they prefer a dark environment like they have on the floor of the rainforest. They love to hide during the day, but will come out to eat.

Can I touch them? They are meant to be pets, and are perfectly safe to handle. A good environment for roaches is a small aquarium or plastic cage with cardboard egg cartons for them to hang out in. You might try picking up one of the egg cartons where a roach is hiding, then either hold the carton so the roach can crawl around on it or let the roach crawl in to your hands. Hold out your hand, keeping your fingers together and flat. Let the roach crawl on you, then slowly lift out your hand and cup it slightly. Remember to wash your hands afterwards, using warm water and soap. Although these insects don’t cause diseases in humans, they may be carrying harmful bacteria, so it is important to wash your hands so that you don’t get sick.

How long do they live? It varies, but species like Orange Spotted Roaches have a lifespan of 18-24 months. The female gives live birth, usually to 20-30 babies at a time. The babies reach maturity in 3-4 months after they are born. While they are growing into adults, they will molt – shedding their outer hard shell, or exoskeleton, and then growing a bigger one.

Will my roaches breed? If you get one male and one female, there is a good chance that they will breed under the right circumstances. If you do not want baby roaches, keep the temperature of the habitat around 70 degrees, or normal room temperature. Adult Orange Spotted Roaches will be fine at this temperature, but they will not mate because their young need higher temperatures to survive. If you would like to see the complete life cycle, you will need to ensure that their habitat has enough heat and humidity.

Feeding Time: What does a pet roach eat? They are omnivores – they eat plants and meat. So a good basic diet contains protein from plants and animals and fiber from grains. You can buy special roach food for them and then to supplement their diet give them fresh fruits and vegetables once a week. Try putting a slice of apple, banana, orange, carrot, potato, or zucchini, or a few spinach leaves in a shallow plastic dish and put it in their habitat. This will provide vitamins and minerals for your pets. Be sure to take the uneaten produce out of the habitat within 48 hours to prevent mold from growing, or attracting ants or fruit flies. A great roach diet would be dry food every day and a fresh food supplement once a week.

Be sure to keep their water dish full. Roaches can live a long time without food, but usually only survive three days without water. The water dish also helps make their habitat more moist and humid. For easiest care, use water absorbent crystals that hold water. You can keep an airtight container of prepared water crystals in a cool place, and add another crystal to the water dish whenever needed (usually every 2-3 days).

If the habitat is hot and humid, the roaches will be more active, which means they will also eat and drink more.

Cleaning Time: You should periodically clean out your pet roach’s habitat to make sure there is no mold growing. Cleaning out the habitat takes only a few minutes and will prevent any bad odors coming from your insects. When is the right time to clean the habitat? When you see small dark roach droppings starting to collect on the bottom, you should clean the habitat out. Usually about once a month is a good time. The minimum should be once every other month.

To clean out the habitat, first remove the roaches. Place them in a container that has smooth sides to prevent them from climbing out. Pick up the roaches one at a time and transfer them to the carton or other container. If a roach is hiding in an egg carton, carefully lift out the carton, then let the roach crawl off into the container or onto your hand. Wash your hands with soap and warm water after touching the roaches.

Take the food and water dishes out, as well as the egg cartons, and place them on paper towels. Rinse the container out and then wash it with a solution of 10 parts warm water to 1 part bleach. Rinse the container again and dry it thoroughly. Place the food and water dishes back in the container. If the cardboard egg cartons seem clean, put them back into the container. Don’t use foam egg cartons. You can also use cardboard tubes in different sizes (mailing tubes, toilet paper tubes, or wrapping paper tubes cut down to shorter lengths) so the roaches can crawl in them. When you’re finished cleaning, throw the used egg cartons away as well as the paper towels. Transfer your roaches back to their habitat, using a flat hand so they can crawl off.

Building a Roach Ranch: If you decide to get a pet roach, you can create a habitat to be as simple or creative as you like. If you wish to make a more natural-looking habitat for your pet roaches to enjoy, you can buy peat moss or coconut husk mulch from a pet store (in the Reptile section). Put in a layer of moss or mulch (about one inch), then add pieces of bark for the roaches to climb on and hide under. This type of Roach Ranch will be similar to the Orange Spotted Roaches’ natural environment in the rainforests of South America.

You can make a Roach Ranch out of cardboard, which can easily be thrown away when it gets dirty. Make a multi-level mansion for your roaches by cutting 3-4 identical shapes (square, rectangle, L-shape) from cardboard. Put separators in between each level – use stacked cardboard strips that are one inch wide and several inches long. Each level should be separated about ½” or three strips of cardboard stacked together. Use Elmer’s glue to attach the separators and flat levels, and let it dry completely (may take up to 24 hours) before putting it in your roach habitat. Add cardboard tubes or crumpled newspaper to complete your Roach Ranch. Remember that it will be easier to clean if roach droppings can fall freely to the ground. When you clean your habitat, check to see if your Roach Ranch is staying clean. Throw away any parts that have been well-used and add new cardboard material for the roaches to climb.

Should I brush my teeth?

Tuesday August 23, 2011

One place where bacteria can be found is on your teeth. This is why it’s so important to brush well. Don’t believe me? Then this experiment is for you. You’ll need to gather your materials and make sure you have a toothbrush and microscope nearby.

This is important because prokaryotes are incredibly common and have a huge impact on our lives. You may already know some of the ways bacteria can be harmful to you, and this is certainly important information. Scientists have used knowledge of prokaryotes to create medications, vaccines, and healthy living habits that have led to a healthier life for billions of people.

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Materials:

water
toothbrush
microscope with coverslips and slides

Experiment:

Place a drop of water on a microscope slide.
Gently brush your toothbrush against your teeth and then apply the saliva from the brush to the slide.
Add a cover slip, and observe under the microscope. Draw what you see.

Here’s a short video on a real bacterial colonization of the mouth after only 8 hours of having a cleaning done at the dentist:

If you’ve ever gone to the store to buy toothpaste, you know there many brands. Do any actually do a better job of getting rid of bacteria on your teeth? This is a great question for the scientific method. Here’s what you do:

Brush your teeth really well.
Swab your teeth with a cotton ball and apply to a petrie dish of agar.The next day, brush with a different brand of toothpaste, and again, swab and apply to a different dish.
Repeat for five days with five different brands. Record the growth of bacteria on each dish for each day.
Remember that “day 1” for the first dish will be different than “day 1” for the second dish, and so on.
Which brand left the fewest bacteria? Could there be factors that caused the difference besides toothpaste brand? (Hint: Do you eat the same thing every day?)

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What Color Light Do Plants Like Best?

Tuesday August 23, 2011

If you’re thinking sunlight, you’re right. Natural light is best for plants for any part of the plant’s life cycle. But what can you offer indoor plants?

In Unit 9 we learned how light contains different colors (wavelengths), and it’s important to understand which wavelengths your indoor plant prefers.

Plants make their food through photosynthesis: the chlorophyll transforms carbon dioxide into food. Three things influence the growth of the plant: the intensity of the light, the time the plant is exposed to light, and the color of the light.

When plants grow in sunlight, they get full intensity and the full spectrum of all wavelengths. However, plants only really use the red and blue wavelengths. Blue light helps the leaves and stems grow (which means more area for photosynthesis) and seedlings start, so fluorescent lights are a good choice, since they are high in blue wavelengths.

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For my fourth grade science project, I placed a box over a plant and poked different colored lights into each upper corner to see which way the plant grew. It turned out that my plant grew toward the blue light the most. When I turned off the red light, my little plant stopped flowering, but started flowering again when the red light turned on.

After doing my homework, I learned that chemicals in my plant respond to light and dark conditions, which means that my little plant could “tell time” by using chemistry. Not the 12-hour clock that we use to tell time with, but they know time over a longer period, like when to flower in a season and when to conserve energy for winter.

I know now that if I had indoor plants, I’d choose fluorescent bulbs high in the blue wavelengths, and I’d also add an incandescent bulb if my plant had flowers I wanted to blossom. Since incandescent also produces heat, I’d also try playing with red LED lights which weren’t available to me when I did my project, but would make an interesting study today!

Here’s a video on what happens if you use a black light with indoor plants:

The scientific method is used by scientists to answer questions and solve problems. Often, good scientific questions are best on things we already know. For example, we know plants need light to grow because the light allows them to make their own food, but what color of light is best? Use the scientific method in the lab below to figure it out.

Experiment:

Place four plants in an area that will get minimal natural lighting.
Do some colors of light help plants grow better than plain white light? Make a hypothesis about this question.
To test things out, grow one plant with plain white light. Grow the other plants with colored light, either by using colored bulbs or by covering white bulbs with tissue paper.
Make daily observations. Which plant grew best? Was your hypothesis correct?

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How to Grow Mushrooms

Tuesday August 23, 2011

If you have ever seen mold growing on an old loaf of bread or eaten a mushroom, you have encountered a fungus. Fungi (that’s the plural of fungus) are a group of organisms, or living things, that are all around us. Mold on bread and mushrooms on pizza are both examples of fungi.

Fungi have an important job. They help break down other material, so that living things are able to grow in soil. This helps make nutritious foods for other organisms. Fungi are needed for life!

Do you think mushrooms are plants? Scientists used to think that all fungi were plants. Now they know that there are some very important different between these two groups of organisms. One of the most important differences is that plants are autotrophic. This means that they can make their own food, just by using the sunlight. Fungi can’t do this. They have to “eat” other living things in order to get the energy they need. This is called being heterotrophic.

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Another difference between plants and fungi is that fungi have cell walls like plants do, but their cell walls are made of chitin. Chitin is a material containing nitrogen that is also found in the shells of animals including beetles and lobsters.

Fungi do not have a vascular system, the system used to transport water and nutrients in plants, but do have hyphae, a structure you will learn about in the next section. Although mold and mushrooms are easy to see, most fungi are a lot harder to see. Some are so small they can only be seen with a microscope.

Others are big enough to see, but live in places that make them hard to find. For example, some fungi live deep in the soil, in decaying logs, inside plants and animals, or even inside or on top of other fungi!

Scientists have estimated that there are 1.5 million species of fungi, and these organisms live all over. Most are found on land, although some do live in water. Some fungi can even live in deserts. No matter their environment, fungi act as decomposers. This means that the fungi break down materials to make their environment better for other organisms to grow.

Humans use fungi for many purposes. One of the most common uses is in food. Mushrooms are eaten by many people on pizza or in salads. But yeast is used in the fermentation process to make beer, wine, and bread.

We’re going to learn how to grow our own mushrooms in this video below. Remember, never eat a mushroom unless you check with an expert first. Poisonous mushrooms look similar to edible ones, so be absolutely certain which kind it is before popping one in your mouth.

NEVER pick wild mushrooms! In addition to the uncertainty in the type of mushroom, there’s also possible harmful bacteria growing on the mushroom.

Fungi are also important in the production of some antibiotics, including penicillin and the chitin in cell walls has been said to have wound healing properties.

Learn more about Kenny and mushrooms from Veggie Gardening Tips!

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Ideas for Exploring Microscopic Life

Tuesday August 23, 2011

Living things are all around us. Sometimes the living things we notice the most are animals, whether its birds chirping in the trees, our pet dogs, or even our fellow human beings. However, most living things are not animals - they include bacteria, archae, fungi, protists, and plants. These organisms are extremely important to learn about. They make life possible for animals, including human beings, by keeping soil ready for growth, and providing oxygen for our survival. No life would be possible without these remarkable organisms.

The prokaryotes, bacteria and archaea represent an amazingly diverse group of organisms only visible when one looks under a microscope. These single-celled organisms obtain energy and reproduce in a variety of ways.

Though some bacteria are harmful, causing disease, many are very helpful, providing the nitrogen we need to live and aiding in digestion. Archaea have been found in some of the most extreme environments on the planets, including environments that are remarkably hot or salty.

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Here are a couple of videos that will give you a few ideas on how to view this amazing world using a compound microscope, UV light, and more. First, we're going to grow our own bacteria, then we'll look how to identify the bacteria already around you.

Grow Your Own Bacteria

Bacteria, both good and bad, are all around. In fact, there are more bacteria in your mouth than people on Earth! See where you can find bacteria in the activity below.

Materials:

petri (petrie) dish
agar
cotton swab
sink or bathtub

Experiment:

1. Prepare your petrie dish of agar.
2. Using your cotton ball, swab a certain area of your house. (Think about what areas might have a lot of bacteria.)
3. Rub the swab over the agar with a few gentle strokes before putting the lid back on and sealing the petrie dish.
4. Allow the dish to sit in a warm area for 2 or 3 days.
5. Check the growth of the bacteria each day by making a drawing and describing the changes.
6. Try repeating the process with a new petrie dish and a swab from under your finger nails or between your toes.
7. Throw away the bacteria by wrapping up the petrie dish in old newspaper and placing in the trash. (Don't open the lid.)

What's happening?

The agar plate and warm conditions provide the ideal place for bacteria to grow. The bacteria you obtained with the cotton ball grow steadily, becoming visible with the naked eye in a relatively short time. Different samples produce different results. What happened when you took a swab sample from your own body?

Want to grow your own bacteria using a hand-washing kit from Home Science Tools?

Is it safe to wash my hands in water?

When you want a glass of water, where do you usually get it from? Do you drink bottled water or get it from the tap? You probably don’t drink from a pond (although people in many countries do.) Why do we have these different ways of getting water? Is there anything really different about bottled water, tap water, and lake water? Let’s find out!

Materials:

three different water samples (see experiment below)
microscope with slides and coverslips
notebook with pencil for sketching

Experiment:

Obtain three water samples – tap water, bottled water, and water from outside. (The “outside” water could be a stream, lake, or just a puddle.)
Make slides using several drops of each water sample.
Observe the slides under the microscope.
Make drawings of what you see, comparing and contrasting each sample.

Is soap better than sanitizer?

In this activity, you will compare the ability of bar soap and hand sanitizer to remove bacteria from your hand. This is another example of using the scientific method to answer questions and solve problems.

Materials:

soap
hand sanitizer
petri dish
agar
cotton call or cotton swab

Experiment:

Wash one of your hands with bar soap and clean the other with a hand sanitizer.
Swab each hand with a cotton ball and rub each swab in a Petrie dish with agar.
Place in a warm place and allow to sit for several days.
Compare the bacteria growth in each plate. Which method of cleaning was more effective?

Learn how well you wash your hands by viewing the germs under a UV light with the Glo Germ kit from Home Science Tools (Do you already have the UV light from Unit 9? Just get the bottle of glow germ gel.)

Here are several additional bonus experiments you can do with the rest of the glo gel you have left over!

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Flu Attack!

Monday August 22, 2011

Ah-chooo! Influenza (the “flu”) is when you get chills, fever, sore throat, muscle pains, headaches, coughing, and feel like all you want to do is lie in bed. The flu is often confused with the common cold, but it’s a totally different (and more severe) virus.

The flu is passed from person to person (or animals or birds) by coughing or sneezing. With plants, it’s transmitted through the sap via insects. In the case of birds and animals, the flu is usually transmitted by touching their droppings, which is why hand-washing is so important! In addition to soap, the flu virus can be inactivated by sunlight, disinfectants and detergents.

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A virus can only replicate inside the living cells of organisms, and most are way too small to be viewed through a microscope. Viruses can infect organisms, animals, plants, bacteria and archaea. Virus particles (virions) are made up of two or three parts, including the genetic material (from either DNA or RNA), long molecules which bring genetic information, and a special coat that protects the genes.

Viruses can be helical or complex structures, but they are a lot smaller than bacteria usually by about a hundredth.

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Magnetic Bacteria

Monday August 22, 2011

Birds, people, plants, and microscopic organisms need to know where they are as well as where they want to be. Birds migrate each year and know which way is south, and plants detect the sun so they can angle their leaves properly. People consult a map or GPS to figure out where they are.

Magnetotactic bacteria orients itself along magnetic field lines, whether from a nearby magnet or the Earth’s magnetic field. It’s like having a built-in internal compass.

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Discovered in 1975, scientists noticed that certain bacteria seemed to move to the same side of the microscope slide. After placing a magnet near the slide, they were able to determine these bacteria contain tiny bits of iron (magnetic crystals, to be exact). The bacteria place the iron (which act like magnets) in a line to make one long magnet, and use this magnet to align to the earth’s magnetic field, just like a compass.

Bacteria move away from oxygen and toward areas with low (or no) oxygen. In water, oxygen levels decrease with depth, so you’ll find magnetotactic bacteria in the deeper parts. These bacteria use their internal compass to figure out which way is deeper.

Since the Earth’s geomagnetic north pole actually points at an angle, the “north-seeking” bacteria aligned to the field lines are also pointing down. When the bacteria move north along the field lines, they are moving into deeper water (with less oxygen). On the flip side (Southern Hemisphere), magnetotactic bacteria must be “south-seeking” in order to go deeper. Of course, at the equator, there’s a mixture of north-seeking and south-seeking bacteria.

Since the magnetic crystals are found in the organisms, even dead cells will align themselves!

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How Bacteria Grow

Monday August 22, 2011

All living things need a way to get energy. Bacteria get their food and energy in many ways. Some bacteria can make food on their own, while others need other organisms.

Some bacteria help other living things as they get energy, others hurt them while they get energy, and still others have no affect on living things at all.
Some living things, or organisms, are able to make their own food in a process called photosynthesis.

In this process, the organism turns energy from the sun into energy that can be used for energy. Organisms that get their energy from photosynthesis are called autotrophs. Some bacteria get their energy this way.

Some bacteria, called chemotrophs, get their energy by breaking down chemical compounds in the environment, including ammonia. Breaking down ammonia is important because ammonia contains the element nitrogen.

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All organisms need nitrogen to survive, and the nitrogen released by bacteria is crucial to these living things’ survival. Clearly, chemotrophs are very important and beneficial to other living things. Living things that cannot get their energy through photosynthesis or from breaking down chemical compounds have to get their energy from other living things. Some bacteria, called decomposers, get their energy by breaking down dead organisms or waste products into simple nutrients and energy.

Pseudomonas bacteria are decomposers found in the soil, where they recycle dead plant material. The last groups of bacteria get energy from organisms that are still alive, and depend on these organisms to survive.
Mutualistic bacteria get their energy in ways that help another organism. For example, some bacteria live in the roots of legumes, including pea plants. The bacteria make the nitrogen the pea plants need and the pea plants provide a place for the bacteria to live. Other bacteria, called parasitic bacteria, hurt the organism they are getting help from. For example, some bacteria cause illness. We will talk about ways bacteria can be helpful or harmful a little later.

All living things reproduce. This is the only way to ensure the organisms continued survival. Bacteria reproduce asexually. This means that a single “parent” organism produces offspring on their own. In the case of bacteria, a process called binary fission is used. In binary fission, the DNA in the nuceleoid region and plasmids double, and the bacterium splits into two identical copies. If everything happens the way it’s supposed to, the two new bacteria will be identical to the original bacterium. These bacteria can then split again to increase the number of bacteria in the population. Through binary fission, bacteria reproduce very quickly. Some populations can double their size in less than ten minutes!

How to Grow Your Own Bacteria

Although we often think of bacteria as things that cause disease, some bacteria are very helpful. In fact, if you like to eat yogurt, you are eating helpful bacteria all the time! See for yourself in these two activities:

Materials:

clean plastic cup
yogurt
dropper or toothpick
microscope with slides and coverslips

Place a very small portion of plain yogurt onto the slide, and add one drop of water. Place the coverslip on top.
Under low power, find a section where the yogurt is pretty thin; this is where you will find the bacteria.
Switch to high power (400X for most microscopes) for a better view of the bacteria.
Make a sketch of your view under different magnifications.

Finding Bacteria in Yogurt

Materials:

clean plastic cup
yogurt
toothpick
water
microscope with slides and coverslips

Clean a small plastic cup. Make sure ALL soap is completely rinsed off.
Put a small amount of yogurt in the cup, and put it aside in a dark, relatively warm area. Leave undisturbed for at least 24 hours.
After the time has past, take a small sample with a toothpick and place on a slide. If the sample seems too thick, dilute with a drop of water. Next, place a cover slip on top.
First observe the bacteria at low power 100X to find a good place to start looking. The diaphragm setting should be very low (small) because these bacteria are nearly transparent.
Switch into the highest power to identify the bacteria according to arrangement.
From here you can identify any bacteria you might find. For example, a common inhabitant of yogurt is a paired, round bacteria or diplococcus (see list below)
Did you observe more bacteria in part 1 or 2? Why do you think this is?
Do you want to take it a step further? Think about all the kinds of yogurt out there. There are different flavors, different brands, some that are non-fat, and much more. Do some types have more bacteria than others? This is a great question to investigate using the scientific method. So come up with a specific question, write a hypothesis, grab some yogurt, and get experimenting!

Bacteria are classified as follows:

First observe the way the bacteria are arranged:

paired = diploe
chained = streptose
clusters = staphyle

Next observe the shape of the bacteria:

round = coccus
rod = bacillus
spiral = spirillum

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Bacteria Micromotor

Monday August 22, 2011

Bacteria have a bad reputation. Walk down the cleaning aisle of any store and you’ll see rows and rows of products promising to kill them. There are definitely some bacteria that cause problems for people, and we’ll talk about them soon, but we are going to start off positive, and talk about the many ways bacteria can be helpful.

First, decomposers help control waste. Without these bacteria, the amount of waste in soil would quickly make the soil a place where nothing could grow. Bacteria are even used in sewage treatment plants to treat our waste. Decomposers also help provide organisms with nitrogen, as was discussed earlier.

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Bacteria also have an important role in the foods we eat. Yogurt and some cheeses are made from using bacteria to ferment milk, and sauerkraut is made from using bacteria to ferment cabbage.

Once we’ve eaten, bacteria continue to help us. Bacteria line the digestive tract and help us digest food. In your gut, the number of bacteria cells is greater than the number of your own cells.

In science labs, researchers have found ways to use bacteria to produce medicines. For example, some people with the disease diabetes need insulin. Mass-produced insulin, made possible by bacteria, has lowered the cost of insulin for people suffering from this disease.

Researchers from Japan’s National Institute of Advanced Industrial Science and Technology (AIST) have figured out a way to get motion from bacteria. This team of scientists have developed a motor that is powered by bacteria movement.

Because this motor is so small (it’s only 20-microns across, where 1 micron = 1 millionth of a meter), we’ve posted a picture (above) so you can see the six revolving motor blades. Each blade has a tab that sits in a circular groove area, which is treated with a substance that makes the bacteria move only in one direction. As the bacteria moves, they push the tabs (which spins the motor). This is a great way to get power for tiny devices, such as tiny pumps inside medical devices.

What is true about bacteria is that they are made of only a single cell, are prokaryotes, and are very common. They are the most common living things on Earth. In fact, there are more bacteria living in the mouth of a single person than there are people on the planet!

Since bacteria are made of only one cell, they are very cell. The only way to see bacteria is to look at them in a microscope. When you look at bacteria in a microscope, they usually have one of three shapes.

Bacilli are shaped like rods, cocci are shaped like spheres, and spirilli are shaped like spirals. Using shapes to describe bacteria helps scientists but bacteria into groups, which is often called classification.

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Amoeba in Action

Monday August 22, 2011

If your kitchen is like most kitchens, you probably have cabinets for cups and pots and pans, along with drawers for silverware and cooking utensils. You might also have a drawer you call the “junk drawer.” The things in this drawer aren’t actually “junk.” If they were, you’d throw them away. Instead, things usually get put here because they just don’t fit anywhere else.

You might be surprised to learn that the system for classifying organisms has its own “junk drawer.” It’s called the protist kingdom. Its members, like the contents of your kitchen junk drawer, are important, but don’t fit nicely in one of the other kingdoms.

Broadly, protists can be classified as animal-like, plant-like, or fungus-like. It is important to remember that being “animal-like” does not make a protist an animal. Such and organism, like plant-like or fungus-like protists, are members of an entirely different group of living things.

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Amoeba are protists that walk using a method called a false foot, or pseudopodia. The amoeba extend a “false foot” and then pull the rest of their body along with them.

Animal-like protists are called protozoa. Like animals, protozoa can move on their own and are heterotrophic. Some protozoa eat by wrapping their bodies around their prey, creating a “food storage compartment.” Toxins are then produced which paralyze the prey, and food moved into the waiting protist.

Other protozoa have flagella, or tails, that assist in feeding. The flagella whip back and forth creating a current that brings food to the protist. Still other protozoa are parasites, and get nutrients from a host organism, harming the host in the process.

Animal-like protists can be classified, or placed into groups, based on how they move. Some move with the aid of a flagellum (that’s the singular form of flagella.) Others have many small tail-like structures called cilia which they move back and forth to get around. Still others have what is known as a “fake foot” or pseudopodia. These protozoa have a part of their cell stretch out, which pulls the rest of the organism along. The amoeba is a common example of this type of protozoan. Finally, some protozoa don’t move at all.

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Giant Veggies!

Monday August 22, 2011

Six-foot zucchini? Ten-foot carrots? Are giant veggies just a photography trick, or are they real?

The happy news is that yes, they’re real! Expert horticulturists have accumulated a great wealth of knowledge about different climates and dirt conditions. They must know about the different chemical, physical and biological properties of gardens and do multiples of experiments dozens of plants. We found an incredible horticulturist, John Evans, who has accumulated over 180 first places in both quality and giant vegetable categories, with 18 State and 7 World Records.

According to John Evans: “If you could, imagine what it would be like to dig up a carrot from your garden and not knowing how big it is until the last minute, and then finding out that it’s 19 lbs. Now that’s exciting!”

John has spent many years developing fertilizers, bio-catalysts, and growing techniques to grow 76-lb cabbages (photo shown left), 20-lb carrots, 29-lb kale, 60-lb zucchini, 43-lb beets, 35-lb broccoli and cauliflowers, and 70-lb swiss chard that was over 9 feet tall and took three people to carry it to the trailer!

Here’s a video on growing giant flowers by a passionate community gardening club:
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So what makes the plants grow so large? Apart from good soil and climate conditions, there are a few tricks you can do in order to encourage growth in plants.The video above shows the effects of using gibberellic acid. So what is that stuff, anyway?

Hormones are chemicals that send messages causing changes in living things. Gibberellic acid is a hormone that makes some pretty noticeable changes. This hormone changes the RNA of plants. RNA is an important molecule that affects which proteins are produced by an organism. By changing proteins, the characteristics of the organism can be changed. In the case of Gibberellic acid, the change in RNA makes cells grow faster and longer. When added to a plant, it makes the plant grow larger than it otherwise would grow. See for yourself!

Plant two lettuce seeds in similar soil in the same general area.
Spray one seed with Gibberellic Acid.
Make daily observations.
How did the control plant (no acid) compare to the experimental plant (with acid)?

Gibberellic acid is very potent, and does occur naturally in plants to controls their development. This is a place where a little bit goes a long way. In fact, if you use only a couple of drops, you’ll see a big effect… too much and the reverse will happen (hardly any growth at all).

Gibberellic acid can do several things, including stimulate rapid growth in the root and stem and trigger mitosis in the leaves. Scientists have used gibberellic acid to start germination in dormant seeds. You’ll also find it used by farmers who need larger clusters of grapes and cherries. Since plants get ‘used to’ gibberellic acid and become less responsive to it over time, you’ll want to use only a little bit on your plants.

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Can Bacteria Get Sick?

Monday August 22, 2011

When you hear the word “bacteria” what do you think of? If you’re like most people, you probably think of things that can make you sick. Although some bacteria do make us sick, this is not true for all of them. In fact, as we’ll see a little later, some bacteria are very helpful.

Did you know that bacteria can have a virus? It’s true! But first, you might be wondering: what’s the difference between viruses and bacteria?

Bacteria grows and reproduces on its own, while viruses cannot exist or reproduce without being in a living cell of a plant, animal, or even bacteria. Size-wise, bacteria are enormous.

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The T4 bacteriophage is a virus that looks like a spaceship from an alien planet. It attaches to the surface of the Escherichia coli (E. coli) bacteria using its six legs and injects DNA into the bacteria. The DNA then tells the bacteria to multiply and essentially fill the bacterial cell to bursting. This is how the T4 kills E. coli.

In this video below, you’ll first see large E. coli bacteria floating around, one of which is attacked by a T4 bacteriophage. Notice how the T4 injects the DNA strand into the bacterium. (What’s not shown is how it bursts, but we’ll leave that to your imagination!)

Some bacteria are responsible for diseases in humans and other organisms. Strep throat, tuberculosis, and pneumonia are all the result of bacteria.

Bacteria can also be responsible for food poisoning. Raw eggs and undercooked meats can contain bacteria that can cause digestive problems. One simple step everyone can take to reduce these kinds problems is washing your hands before cooking or eating. Cleaning cooking surfaces and fully cooking food can also help.

In 2007 the United States Food and Drug Administration (FDA) approved using bacteriophages on all food products. Other places you’ll find bacteriophages are in hospitals, uniforms, sutures and surgery surfaces where it’s important to keep surfaces very clean.

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How to Ripen a Tomato with a Banana

Monday August 22, 2011

It drives me crazy it when my store-bought tomatoes go straight from unripe to mush. After talking with local farmers in my area, I discovered a few things that might help you enjoy this fruit without sacrificing taste and time.

Grocery store owners know that their products are very perishable. If the tomatoes arrive ripe, they might start to rot before they can get on the shelf for the customer. Ripe tomatoes are near impossible to transport, which means that farmers often pick unripe (green and therefore very firm) tomatoes to put on the truck. Grocery stores prefer hard, unripe tomatoes so their customers can get them home safely.

The problem is, how do you enjoy a tomato if it’s not ready?

Scientists and food experts ripen tomatoes quickly with ethylene while they are in storage. As the gas surrounds the green tomato, it chemical reacts to speed up the ripening process, causing the tomato to soften and change color to red or orange.

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The color change in this video is subtle – can you tell the difference between the beginning and end?

Another hormone involved in plants is ethylene. Ethylene is an unusual hormone because it is a gas. What does this mean? Find out using a fruit with plenty of ethylene, a ripe banana.

Materials:

green banana
very ripe banana
paper bag

Experiment:

Place one green banana in a paper bag.
Place another green banana in a paper bag, along with a very ripe banana.
Make daily observations about each banana.
What’s causing the differences you see? (Hint: Think about ethylene and how it can travel.)

What’s Happening: In the bag with two bananas, the gas travels from one to the other, ripening it.

Ethylene, a hydrocarbon gas like propane and butane, is generated by other fruits like bananas. When you store a banana next to a tomato, the banana’s gas triggers the ripening process in the tomato. Scientists have found that tomatoes ripened this way keep longer, but farmers and customers have found that these tomatoes have less flavor and mushier texture.

If you’ve noticed the recent vine-ripened tomato trend at the grocery store, it’s because those tomatoes tend to have more flavor than the green ones picked from the vine and stored in a room of ethylene gas.

When you’re at home, keep fully ripe tomatoes out of the refrigerator, as they are best kept at room temperature on your counters. If you stick a tomato in the fridge, you’ll find it less flavorful and starting to have a starchier texture.

Experiment:

Place a green tomato in a bag with a banana.
Make daily observations about the tomato and banana.
How did the banana take to ripen?

The bottom line? Use the banana-gas trick for tomatoes you cook or bake with, and enjoy your fresh tomatoes straight from the vine and stored on your countertop.

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Real Slime: Orange Bacteria

Monday August 22, 2011

This type of slime Physarum Polycephalum is called the “many-headed slime”. This slime likes shady, cool, moist areas like you’d find in decaying logs and branches. Slime (or slime mold) is a word used to define protists that use spores to reproduce. (Note: Slime used to be classified as fungi.)

Real slime lives on microorganisms that inhabit dirt, grass, dead leaves, rotting logs, tropical fruits, air conditioners, gutters, classrooms and laboratories. Slime can grow to an area of several square meters.

Slime shows curious behaviors. It can follow a maze, reconnect itself when chopped in half, and predict whether an environment is good to live in or not. Scientists have battled with the ideas that at first glance, slime appears to be simply a “bag of amoebae”, but upon further study, seem to behave as if they have simple brains, like insects.

Slime can be either a plasmodial slime, a bag of cytoplasm containing thousands of individual nuclei, or a cellular slime which usually stays as individual unicellular protists until a chemical signal is released, causing the cells to gather and acts as one organism.
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Slime feeds by surrounding its food completely and secreting enzymes to digest it. If the slime dries out before its finished eating, it will form a hard tissue shell to protect the dormant slime until the weather turns wet again. The cool part is that the slime will continue searching for food once it hydrates and softens up. When slime can’t find food, it will begin the reproductive phase. Spores form from the mitosis phase and are spread by wind currents. Spores can remain formant for years if the conditions are unfavorable.

Scientist have discovered that physarum polycephalum (orange slime) seems just as intelligent as some insects! A team researchers set up a maze (made of agar) and found that the slime found the shortest possible path to the food.

Another team of scientists are working on bio-computing devices, which use slime instead of semiconductors. The scientists found that slime reacts consistently to certain stimuli. (If they poke it here, it moves to the left…) This team is also figuring out how to precisely point and steer slime using light and food sources.

What this means is that you’ve got a creature that will always emerge from a maze the same way when dropped in at random, is direction-controllable, and always reacts to stimuli the same way. Sounds like the inner workings of a computer, doesn’t it?
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Yeast, Mold, and More!

Sunday August 21, 2011

Fungi and protists, including mold, moss, yeast, and mushrooms, are found all around us. One common group of fungi is mold. Mold, like all fungi, are heterotrophs, which means they rely on other living things for their energy. This is different than an autotroph like a plant, which gets its energy from the sun.

Mold commonly grows on bread, getting food from this source. What do you think makes mold grow? Being in a dark place? Being exposed to moisture? Something else? The scientific method is a series of steps some scientists use to answer question and solve problems. To conduct an experiment based on the scientific method, you must have a control sample, which has nothing done to it, and several experimental samples, which have changes made to them. You can then observe results in the experimental sample to see how your changes to them affect results.

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Materials:

water
paper towel
slices of bread
plastic wrap
pie dish or plate
microscope with slides and coverslips (optional)

Here’s what you do:

Place a wet paper towel on the bottom of a pie tin
Add a slice of bread
Cover with plastic wrap and place in a dark place for three days
Take the pie tin out and make observations
What organisms do you think you see?

In the dark environment, mold grows on the bread. The exact type of mold will be different depending on the type of bread. Is there a difference between white and wheat? Organic and Wonder Bread? Now let’s take this a step further:

Take five pieces of bread. Place one in a pie tin and leave it on the kitchen counter. This is your “control” bread.
Place the other pieces of bread in pie tins and do something you think will help make mold grow. These are experimental samples.
Every day, observe each slice of bread and take notes.
What made the mold grow fastest? Did anything slow down mold growth, and form less mold than the control?
What does this tell us about food storage?

You probably found that mold grows well in the dark, and warm conditions. So, if you want to make your bread last longer, keep it cool and out of the dark.

Build an Ecosystem

Protists can be classified as animal-like, plant-like, and fungus-like. Animal-like protists are able to move and are heterotrophic, relying on other organisms for food. Many protozoa live in grasses, especially those found in lakes, rivers, and streams, where they are able to get the nutrients they need to survive. Create your own mini-ecosystem of these remarkable creatures in the activity below.

Materials:

grass
clean, empty glass jar
microscope with slides (optional)

Experiment:

Add water and a handful of grass to the jar
Put the lid on the jar but don’t seal it all the way
Keep the jar in a dark area for three days
Take it out and make observations. If possible, observe the organisms under a microscope.

Protozoa and other protists live of the grass, and increase in number after the jar is in the dark for several days.

Fun with Yeast

There are over 1,500 species of yeast currently discovered, and scientists estimate that this is only 1% of all yeast species. Most reproduce by budding, although a few use mitosis. Most yeasts are single-celled, although the multicellular varieties use a string to connect budding cells (pseudohyphae or false hyphae). Yeast is a fungus used in cooking many products, including bread. Why is yeast important in the baking process? Let’s find out!

Materials:

yeast
zipper-type sandwich bag
warm water
sugar

Experiment:

Put about a teaspoon of yeast into a sandwich bag.
Add about three spoons of sugar and about half a cup of very warm water. If you stick your finger into the water, it should feel warm but comfortable.
Squeeze out as much air as you can and then seal the bag. Place it in a warm spot
After about 5 minutes, you should start to see tiny bubbles forming. After 15 minutes, you should see quite a few more bubbles. After an hour, the bag should be inflated quite a bit.

Imagine that the yeast is inside some bread dough instead of the bag. As it changes the flour into sugar and consumes it, it gives off carbon dioxide and alcohol. Your bread will not be alcoholic, but when the alcohol cooks away, it leaves behind flavors that add to the taste of the bread.

More Ideas!

What happens if you place leftover food in three different cups and placed one of the cups on a sunny windowsill, another cup in the refrigerator, and a third cup in a dark cupboard? What if you use a magnifier? How does light or temperature affect the mold’s growth? Are the molds all the same color, or are they different?

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Plant Press

Sunday August 21, 2011

Art and science meet in a plant press. Whether you want to include the interesting flora you find in your scientific journal, or make a beautiful handmade greeting card, a plant press is invaluable. They are very cheap and easy to make, too!

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Here’s what you need:

Newspaper
Cardboard
Belt buckle or large, strong rubber bands
Sheets of paper

Download Student Worksheet & Exercises

Here’s how you make it:

Cut the cardboard into square pieces.
Cut or fold the sheets of newspaper into squares the same size as the cardboard.
Place 4 sheets of newspaper between each piece of cardboard. You can also use white copy paper.
Place the plants you want to press in between the newspaper.
If you want, you can sandwich the plant press with the wood planks for added pressure.
Bind it tightly with the rubber bands or a belt buckle.
Leave it in a dry place for two to four days.

How does it work? The pressure from the rubber band/string pushes the water from the plants. The water is then absorbed by the newspaper. Since the pressure is the key to the press, it’s important not to open the press for at least two days (more is better).

Troubleshooting: The press works by pushing the moisture out of the plants, so any way moisture can stay in (or get back in) to the plants will make the press less effective. First, storing the press in a dry place is essential. If the press is left in a moist area not only will in not work, but it will grow mold and ruin the press and the plants. Conversely, if the pressure is not great enough, the moisture will not be pressed out. Thus make sure that the plants fit in the press, are bound tightly, and that the press is stored in a dry area for at very least two days.

Exercises

Draw and describe the functions of the following plant parts: root, stem.
What two major processes happen at the leaf?
Why are flowers necessary?
Do all plants have roots, stems, leaves and flowers?

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Monocots and Dicots

Saturday August 20, 2011

Flowering plants can be divided into monocotyledons and dicotyledons (monocots and dicots). The name is based on how many leaves sprout from the seed, but there are other ways to tell them apart. For monocots, these will be in multiples of three (wheat is an example of a monocot). If you count the number of petals on the flower, it would have either three, six, nine, or a multiple of three. For dicots, the parts will be in multiples of four or five, so a dicot flower might have four petals, five petals, eight, ten, etc.

Let's start easy...grab a bunch of leaves and lets try to identify them. Here's what you need to know:

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Materials:

lettuce or celery
sharp knife with adult help
cutting board
microscope with slides
flowers of your choice

Download Transpiration Lab (for Monocots & Dicots)

Further Experiments:

Source: Wiki

Most monocots have veins that are parallel, running side by side. To see an example of this, look at a blade of grass. Most dicots have leaves with veins that form networks. Look at the leaf of lettuce, or a leaf from an oak or maple tree. This is not an absolute test, but it will usually put you on the right path.
Another test involves cutting the plant's stem. Use a sharp knife to cut through the stem, and then examine it with a magnifying glass or microscope. You are looking for the vascular tissue that carries food and water through the plant. For dicots, the vascular tissue are arranged in rings or lines. For an easy example of that, chop some celery. The "strings" in the celery is the vascular tissue, and you will find them lined up in a nice row. That tells us that celery is a dicot. For monocots, the vascular bundles are spread through the entire stem. While you are chopping your celery, chop some hearts of palm or some bamboo shoots. Neither will have that distinctive row of vascular tubes, since palms and bamboo are both monocots.
Head for your local grocery store. Look through the produce section, and you should find a wide variety of both monocots and dicots. Most groceries also have a section for live flowers, which will give you a great chance to count some petals.
Look at your flowers. Which are monocots and which are dicots? Why?

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Einstein’s Garden

Saturday August 20, 2011

Mass and energy are conserved. This means you can’t create or destroy them, but you can change their location or form.

Most people don’t understand that the E energy term means all the energy transformations, not just the nuclear energy.

The energy could be burning gasoline, fusion reactions (like in the sun), metabolizing your lunch, elastic energy in a stretched rubber band… every kind of energy stored in the mass is what E stands for.

For example, if I were to stretch a rubber band and somehow weigh it in the stretched position, I would find it weighed slightly more than in the unstretched position.

Why? How can this be? I didn’t add any more particles to the system – I simply stretched the rubber band. I added energy to the system, which was stored in the electromagnetic forces inside the rubber band, which add to the mass of the object (albeit very slightly). Read more about this in Unit 7: Lesson 3.

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For plants, this means that energy from captured sunlight, combined with carbon dioxide and water, both of which have mass, make the plant heavier. Let’s find out how Einstein would have planted a garden while thinking about his big ideas.

Materials:

scale for weighing your plant
pot with soil
plant (not potted yet)
water
time
notebook and pencil to record your findings

Download Student Worksheet & Exercises

Prepare a pot with dirt. Add a measured amount (like 1 cup) of water to dampen the soil. Weigh the pot filled with soil (but no plant).
Add a plant to the pot and weigh the whole thing.
Subtract the weight you found in step 1 from step 2 to find out how much the plant weighs.
You’ll be weighing your pot each day. Weigh the plant before watering (water it the same amount each day) and write it down in your notebook . If you’re giving it water and sunlight, the plant should be getting heavier.
Where does this mass come from? You can’t create mass, and yet the plant is getting heavier. How?

You and I get heavier when we eat food. You aren’t giving the plant food, but it is getting food. How? Where does its food come from? The energy from the sun is changed to sugars during photosynthesis, increasing the mass of the plant.

Exercises

Where does this mass come from? You can’t create mass, and yet the plant is getting heavier. How?
Can energy be created?
Can energy be destroyed?

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Carnivorous Greenhouse

Saturday August 20, 2011

Plants need light, water, and soil to grow. If you provide those things, you can make your own greenhouse where you can easily observe plants growing. Here’s a simple experiment on how to use the stuff from your recycling bin to make your own garden greenhouse.

We’ll first look at how to make a standard, ordinary greenhouse. Once your plants start to grow, use the second part of this experiment to track your plant growth. Once you’ve got the hang of how to make a bottle garden, then you can try growing a carnivorous greenhouse.
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Materials:

2 liter bottle
scissors or razor
gravel or sand
spanish moss
dish or plate
seeds of your choice

Experiment:

Using an exacto knife or scissors, cut the label from the soda bottle. Carefully cut the bottle in half so that the bottom (container) piece is deep enough to hold soil and plants. Poke a few holes into the bottom of the container for drainage.
Fill the bottom of the bottle with a half cup of sand or gravel to provide drainage. Use playground sand, aquarium gravel or small stones picked up from a hike. If sand or gravel isn’t available, crush an old clay pot and use that. (Let an adult crush the pot.)
Place a 1-inch layer of Spanish or Spaghnum moss in the mini greenhouse to keep the soil from mixing with the rock layer. Place a thick layer of potting soil on top of the moss, at least 4 inches deep or 1 inch from the top. Tamp down lightly with your finger
Put the top half of the soda bottle back on, tucking inside the edges of the container. If necessary, you can cut small slits into the upper portion to make it fit. Leave the cap on.
Place atop a waterproof plate in a sunny spot and water sparingly. The lid retains moisture and heat, so your seeds should sprout quickly. Because the plastic is clear, you’ll be able to see the roots beneath the surface of the soil. If the greenhouse gets too steamy, you can remove the lid once in a while. When your seedlings get big enough, transplant to the garden, and plant a new crop!

Tracking Plant Growth

You know that plants grow… but when a plant grows, is the entire stem getting longer, like rolling dough, or is only the tip growing, like squeezing the end of a toothpaste tube?

This simple experiment can give you the answer. Ready?

Tie string around the edge of a plants stem, between the last leaf at the end, and the next leaf.
Make observations as the plant grows.

What’s going on? If the entire stem grows, your string will always stay at the end. If just the tip grows, the string will become further and further from the edge. Which is it? Are you surprised?

Carnivorous Greenhouse

Was the last activity too tame for you? You’ll need to order carnivorous plant seeds. Carnivorous plants are heterotrophs. As you learned, this means they must get their energy from other organisms instead of the sun. Such plants are good at catching small animals, such as insects, to eat. Used the video below to learn how to plant the seeds that will produce these carnivores, and how to care for them once they have sprouted.

Download Student Worksheet & Exercises

Exercises

What is a carnivorous plant?
What is another name for a carnivorous plant?
What does a carnivorous plant need to thrive?
Should we fertilize a carnivorous plant? Why or why not?

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The Science of Broccoli

Saturday August 20, 2011

Broccoli, like all plants, has chlorophyll, making it green. You can really “see” the chlorophyll when you boil broccoli. This is such a simple experiment that you can do this as you prepare dinner tonight with your kids. Make sure you have an extra head of broccoli for this experiment, unless you really like to eat overcooked broccoli.

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First, boil a pot of water. Add some cut up broccoli, and immediately observe the color. Allow the broccoli to cook for 15 minutes, and observe the color again.

What’s happening? When you first put the broccoli in the boiling water, the hot water allowed air bubbles to escape. This allowed you to clearly view chlorophyll, the chemical that makes broccoli green, so the broccoli should have appeared very bright.

After 15 minutes of cooking, chlorophyll undergoes a chemical change and the broccoli becomes a duller color. The heat makes it easy for the chlorophyll to lose magnesium. The magnesium is replaced by hydrogen from natural acids in the plant. This chemical change causes the color to change.

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Turning Compost into Gold

Sunday July 24, 2011

If you have a backyard garden, be sure to give it plenty of sunshine, water, and garbage.

Wait… garbage? Yes, you read that right.

Garbage like rotting food and coffee grounds, made into compost, can be highly beneficial to garden plants. Why? It all has to do with nitrogen.

Plants need nitrogen in order to survive. There is plenty of nitrogen in the atmosphere; the problem is that plants can’t use it in the form found in the atmosphere. For this, bacteria are needed. Bacteria “fix” nitrogen, meaning that they change it into a usable form.

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This is where the garbage comes in. Bacteria break down the garbage by eating it. When other organisms living in the soil, particularly worms, eat the bacteria, the nutrients they have stored up are released. The result is soil far more rich in nutrients.

So, how do you create your own compost pile to create plenty of garbage for your garden’s bacteria to enjoy? Well, you already have the garbage, which is a good first start. Next, you’ll want to get a compost bin. Garden supply stores sell bins, although you could also make one with wood and chicken wire. For even simpler compost bins, a pit in the ground or plastic garbage bag with holes in it will work, although you’ll need to be sure to air out the plastic bag every couple days.

Fill your bin with 1/3 brown material (dead leaves or plants are good), 1/3 vegetation, and 1/3 soil. Then, pile on the garbage! Add kitchen waste, grass clippings, dry leaves, dead plants, shredded newspaper, lint from your clothes dryer, and pet hair. The ideal compost heap will have a 25 to one ratio of things like dead leaves and newspapers, which are high in carbon to grass and other plants, which are high in nitrogen. Adding cattle, horse, or chicken manure is a great idea. Trash to avoid are bones, meat, and fat (all of which can attract pests), human or pet waste (which can spread disease), and weeds or diseased plants (which can re-introduce the weed or disease into your garden.)

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Keep your compost heap moist, but not soggy and turn it with a pitchfork or spade to add air into the mix. Once your compost bin is going strong, you can add it to your garden for improved plant growth!

Three Ways to Create a Plant

Sunday July 24, 2011

If you’ve ever eaten fruits or vegetables (and let’s hope you have), you have benefited from plants as food. Of course, the plants we eat have been highly modified by growers to produce larger and sweeter fruit, or heartier vegetables.

There are three basic ways to create plants with new, more desirable traits:

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Grafting

Grafting takes advantage of the fact that trees have the ability to heal themselves. In this method, a branch of a tree is cut off and replaced with the branch of a different tree. Wait a season and, voila, a new tree with the traits of the branch that was added on, or grafted, is growing on the original tree.

There are many reasons for grafting. First, it allows growers to produce a tree with more than one type of fruit. Peaches, plums, and apricots can all be found on the same tree after grafting has occurred. Grafting of the same fruit can also beneficial. Sweet oranges are preferred for taste, but trees that produce these types of oranges are at greater risk for disease. Also, sweet oranges often have no seeds, making it impossible for them to reproduce naturally. By grafting sweet oranges onto sour orange trees, both problems can be avoided.

Hybridization

You’ve probably noticed that children look like their parents, and that brothers and sisters tend to look alike as well. We share more traits with the people we are most closely related to. This is the basic idea of the branch of science called genetics. It’s not just true with people, though. Plants will share traits with their offspring.

Breeders have been using the ideas of genetics for years. They have been forcing plants with traits people find desirable to breed, hoping that the offspring will share those traits. Traits such as resistance to disease, large size, and sweetness, are bred for. When breeders began doing this, they didn’t know about genes, the factors that carry traits from parents to offspring. As this became known, breeders became better at making crosses that would produce the traits they were looking for.

Transgenics

Every living thing has a genome. A genome is the complete sequence of genes the organism has. The genes of each organism are different, which is why a bacterium is different than, say, a tomato. For the most part, that’s a good thing. We wouldn’t want our tomatoes to be much like bacteria. But what if we did? At least a little. If there was something in bacteria that would be helpful to tomatoes, would there be a way to add the bacteria gene to the tomato genome? It turns out that the answer is yes, and transgenics refers to the process of adding something helpful to another organism’s genome.

In the case of the bacteria and the tomato, some bacteria have a gene that would give tomatoes resistance to disease. This gene has been placed in many tomatoes. Some people have concerns about transgenics, worrying that adding to genomes could have unintended consequences. Nevertheless, this process has become very common.

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Ferrofluid

Friday July 1, 2011

A ferrofluid becomes strongly magnetized when placed in a magnetic field. This liquid is made up of very tiny (10 nanometers or less) particles coated with anti-clumping surfactants and then mixed with water (or solvents). These particles don’t “settle out” but rather remain suspended in the fluid.

The particles themselves are made up of either magnetite, hematite or iron-type substance.

Ferrofluids don’t stay magnetized when you remove the magnetic field, which makes them “super-paramagnets” rather than ferromagnets. Ferrofluids also lose their magnetic properties at and above their Curie temperature points.

Ferrofluids are what scientists call “colloidal suspensions”, which means that the substance has properties of both solid metal and liquid water (or oil), and it can change phase easily between the two. (We as show you this in the video below.) Because ferrofluids can change phases when a magnetic field is applied, you’ll find ferrofluids used as seals, lubricants, and many other engineering-related uses.

Here’s a video on toner cartridges and how to make your own homemade ferrofluid. It’s a bit longer than our usual video, but we thought you’d enjoy the extra content.

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Download Student Worksheet & Exercises

Engineering and scientists use ferrofluids to make a liquid seal in hard disks around the spinning disks to keep out dust and grit (hard drives must be kept exceptionally clean!). They do this by adding a layer of ferrofluid between the rotating shaft and magnets which surround the shaft.

You can also use ferrofluids to reduce friction, the way ice and water are used in ice skating rinks. If you coat a strong magnet with ferrofluid, you can get it to glide across a smooth surface like a hockey puck.

NASA uses ferrofluids in the flight instruments for spacecraft, also!

Each particle of ferrofluid is like a each grain or a micro-magnet, which not only interacts with magnetic fields, but also with light.

With loudspeakers, the large magnets that interacting with the coil often heat up. If we replace the magnet with ferrofluid (which is a liquid, remember!) it will actively conduct the heat away from the coil and cool it down because cold ferrofluid is more strongly attracted than hot, and thus the cooler fluid flows toward the coil, and the warmer fluid moves away from the coil.

Exercises

Is the ferrofluid a solid or a liquid?
Does the strength of a magnet matter?
What would happen if the magnet went over the rim of the cup?
Does the ferrofluid have a north and south pole?
What happens if you bring a compass near the ferrofluid?
Name three specific ways ferrofluid makes our lives easier. How might you use a ferrofluid if you were inventing something?

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Instant Ice

Thursday June 30, 2011

Supercooling a liquid is a really neat way of keeping the liquid a liquid below the freezing temperature. Normally, when you decrease the temperature of water below 32^oF, it turns into ice. But if you do it gently and slowly enough, it will stay a liquid, albeit a really cold one!

In nature, you’ll find supercooled water drops in freezing rain and also inside cumulus clouds. Pilots that fly through these clouds need to pay careful attention, as ice can instantly form on the instrument ports causing the instruments to fail. More dangerous is when it forms on the wings, changing the shape of the wing and causing the wing to stop producing lift. Most planes have de-icing capabilities, but the pilot still needs to turn it on.

We’re going to supercool water, and then disturb it to watch the crystals grow right before our eyes! While we’re only going to supercool it a couple of degrees, scientists can actually supercool water to below -43^oF!

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Materials:

water
glass
bowl
ice
salt

Download Student Worksheet & Exercises

Don’t mix up the idea of supercooling with “freezing point depression”. Supercooling is when you keep the solution a liquid below the freezing temperature (where it normally turns into a solid) without adding anything to the solution. “Freezing point depression” is when you lay salt on the roads to melt the snow – you are lowering the freezing point by adding something, so the solution has a lower freezing point than the pure solvent.

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Hot Ice Sculptures

Thursday June 30, 2011

Did you know that supercooled liquids need to heat up in order to freeze into a solid? It’s totally backwards, I know…but it’s true! Here’s the deal:

A supercooled liquid is a liquid that you slowly and carefully bring down the temperature below the normal freezing point and still have it be a liquid. We did this in our Instant Ice experiment.

Since the temperature is now below the freezing point, if you disturb the solution, it will need to heat up in order to go back up to the freezing point in order to turn into a solid.

When this happens, the solution gives off heat as it freezes. So instead of cold ice, you have hot ice. Weird, isn’t it?

Sodium acetate is a colorless salt used making rubber, dying clothing, and neutralizing sulfuric acid (the acid found in car batteries) spills. It’s also commonly available in heating packs, since the liquid-solid process is completely reversible – you can melt the solid back into a liquid and do this experiment over and over again!

The crystals melt at 136^oF (58^oC), so you can pop this in a saucepan of boiling water (wrap it in a towel first so you don’t melt the bag) for about 10 minutes to liquify the crystals.

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Materials:

Sodium Acetate
Disposable aluminum pie plate

Download Student Worksheet & Exercises

You have seen this stuff before – when you combined baking soda and vinegar in a cup, the white stuff at the bottom of the cup left over from the reaction is sodium acetate. (No white stuff? Then it’s mixed in solution with the water. If you heat the solution and boil off all the water, you’ll find white crystals in the bottom of your pan.) The bubbles released from the baking soda-vinegar reaction are carbon dioxide.

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Salty Eggs

Thursday June 30, 2011

Did you know that most people can’t crack an egg with only one hand without whacking it on something? The shell of an egg is quite strong! Try this over a sink and see if you can figure out the secret to cracking an egg in the palm of your hand…(Hint: the answer is below the video – check it out after you’ve tried it first!)

How can you tell if an egg is cooked or raw? Simply spin it on the counter and you’ll get a quick physics lesson in inertia…although you might not know it. A raw egg is all sloshy inside, and will spin slow and wobbly. A cooked egg is all one solid chunk, so it spins quickly. Remember the Chicken and the Clam experiment?

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Materials:

hard-boiled egg
glass
water
salt

Download Student Worksheet & Exercises
This experiment is all about density. Density is basically how tightly packed atoms are. Mathematically, density is mass divided by volume. In other words, it is how heavy something is, divided by how much space it takes up. If you think about atoms as marbles (which we know they’re not from the last lessons but it’s a useful model), then something is more dense if its marbles are jammed close together.

For example, take a golf ball and a ping pong ball. Both are about the same size or, in other words, take up the same volume. However, one is much heavier, has more mass, than the other. The golf ball has its atoms much more closely packed together than the ping pong ball and as such the golf ball is denser.

Here’s a riddle: Which is heavier, a pound of bricks or a pound of feathers? Well, they both weigh a pound so neither one is heavier! Now, take a look at it this way, which is denser, a pound of bricks or a pound of feathers? Aha! The pound of bricks is much denser since it takes up much less space. The bricks and the feathers weigh the same but the bricks take up a much smaller volume. The atoms in a brick are much more squooshed together then the atoms in the feathers.

Back to the experiment – have you ever noticed you how float a lot easier in the ocean than the lake? If so, then you already know how salt can affect the density of the water. Saltwater is more dense that regular water, and your body tissues contain water (among other things).

Did you know that thinner people are more dense than heavier people? For example, championship swimmers will sink and have to work harder to stay afloat, but the couch potato next door will float more easily in the water.
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Rubber Eggs

Thursday June 30, 2011

If you soak chicken bones in acetic acid (distilled vinegar), you’ll get rubbery bones that are soft and pliable as the vinegar reacts with the calcium in the bones. This happens with older folks when they lose more calcium than they can replace in their bones, and the bones become brittle and easier to break. Scientists have discovered calcium is replaced more quickly in bodies that exercise and eating calcium rich foods, like green vegetables.

This is actually two experiments in one – here’s what you need to do:

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Materials:

hard boiled egg
glass or clean jar
distilled white vinegar

Download Student Worksheet & Exercises

When you first plop the egg in the vinegar, do you notice the tiny bubbles? The acetic acid (distilled vinegar) reacts with the calcium carbonate in the eggshell, and you may even notice a color change over a couple of days.

How high does your egg bounce? Does it matter how long you leave it in the vinegar for?

The second part of this experiment is to try this again, but now use a raw egg (wash your hands after handling your egg due to salmonella!) You’ll get a difference result – the eggshell will become flexible, but don’t bounce them.

Exercises

Describe what the eggshell looked like before the reaction.
Describe the acetic acid
The product you witnessed in this chemical reaction was carbon dioxide, a colorless, odorless gas. How can you tell there really was a chemical reaction?
Why did the egg turn to “rubber?”

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Laser Microscope

Thursday June 30, 2011

Did you know that you can use a laser to see tiny paramecia in pond water? We’re going to build a simple laser microscope that will shine through a single drop of water and project shadows on a wall or ceiling for us to study.

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Here’s how it works: by shining a laser though a drop of water, we can see the shadows of objects inside the water. It’s like playing shadow puppets, only we’re using a highly concentrated laser beam instead of a flashlight.

If you’re wondering how a narrow laser beam spreads out to cover a wall, it has to do with the shape of the water droplet. Water has surface tension, which makes the water want to curl into a ball shape. But because water’s heavy, the ball stretches a little. This makes the water a tear-drop shape, which makes it act like a convex lens, which magnifies the light and spreads it out:

Here’s how to make your own laser microscope:

Materials:

red or green laser (watch video for laser tips)
large paperclip
rubber band
stack of books
white wall
pond water sample (or make your own from a cup of water with dead grass that’s been sitting for a week on the windowsill)

Download Student Worksheet & Exercises

Exercises

Does this work with other clear liquids?
What kind of lens occurs if you change the amount of surface tension by using soapy water instead?
Does the temperature of the water matter? What about a piece of ice?
Does this work with a flashlight instead of a laser?
Do lasers hurt your eyes? How?

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Cool Milk Trick

Thursday June 30, 2011

Have you ever tried washing dishes without soap? It doesn’t work well, especially if there’s a lot of grease, fat, or oil on the dish!

The oils and fats are slippery and repel water, which makes them a great choice for lubration of bearing and wheels, but lousy for cleaning up after dinner.

So what’s inside soap that makes it clean off the dish? The soap molecule looks a lot like a snake, with a head and a tail. The long tail loves oil (hydrophobic) and the head loves water (hydrophilic). The hydrophilic end dissolves in water and the hydrophobic end wraps itself around fat and oil in the dirty water, cleaning it off your dishes.

Let’s do an experiment that will really make you appreciate soap and fat:

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Materials:

whole milk (if you have it – otherwise, use lowfat)
food dye
bowl
liquid soap

Download Student Worksheet & Exercises

While it may not look like it (or taste like it), milk is mostly water with minerals, proteins, and fat trapped inside. When you add a drop of soap, the hydrophobic end races around and grabs the fat and links up with other tail ends of soap molecules, forming the colors you see in the dish. The higher the fat content of your milk, the longer the show.
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Introduction to Creating a Homemade Weather Station

Wednesday June 29, 2011

Being able to predict tomorrow's weather is one of the most challenging and frequently requested bits of information to provide. Do you need a coat tomorrow? Will soccer practice be canceled? Will the crops freeze tonight?

Scientists use different instruments to record the current weather conditions, like temperature, barometric pressure, wind speed, humidity, etc. The real work comes in when they spend time looking over their data over days, months, even years and search for patterns.

But where does the weather station get its weather from?

One of the greatest leaps in meteorology was using numbers to predict the flow of the atmosphere. The math equations needed for these (using fluid dynamics and thermodynamics) are enough to make even a graduate student quiver with fear. Even today's most powerful computers cannot solve these complex equations! The best they can do is make a guess at the solution and then adjust it until it fits well enough in a given range. How do the computers know what to guess?

Several weather stations around the world work together to report the current weather every hour. These stations can be land-based, mounted on buoys in the ocean, or launched on radiosondes and report back to a home station as they rise through the different layers of the atmosphere. Pilots will also give weather reports en route to their destination, which get recorded and added to the database of weather knowledge.

We're going to build our own homemade weather station and start keeping track of weather right in your own home town. By keeping a written record (even if it's just pen marks on the wall), you'll be able to see how the weather changes and even predict what it will do, once you get the hang of the pattern in your local area. For example, if you live in Florida, what happens to the pressure before the daily afternoon thunderstorm? Or if you live in the deserts of Arizona, what does a sudden increase in humidity tell you?
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This is an introductory video that will get you started making your own weather station:

Once you have your weather station up and working, you can make another and send set it up at a friend's house or a distant relative. Ask them to read you the instruments when you call them so you can have more than one weather tracking station!

By understanding how the atmosphere moves and changes, scientists can guess on what it will do tomorrow based on what it's done in the past. Even with our massive super-computers today, people are still required to make certain calculations and decisions as to which set of math equations best fit (model) what the weather's currently doing. Maybe one day computers will be able to do this, but we're not there yet.
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Cloud Tracker Weather Instrument

Wednesday June 29, 2011

One of the most remarkable images of our planet has always been how dynamic the atmosphere is a photo of the Earth taken from space usually shows swirling masses of white wispy clouds, circling and moving constantly. So what are these graceful puffs that can both frustrate astronomers and excite photographers simultaneously?

Clouds are frozen ice crystals or white liquid water that you can see with your eyes. Scientists who study clouds go into a field of science called nephology, which is a specialized area of meteorology. Clouds don’t have to be made up of water – they can be any visible puff and can have all three states of matter (solid, liquid, and gas) existing within the cloud formation. For example, Jupiter has two cloud decks: the upper are water clouds, and the lower deck are ammonia clouds.

We’re going to learn how to build a weather instrument that will record whether (weather?) the day was sunny or cloudy using a very sensitive piece of paper. Are you ready?

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Materials:

Sun print paper or other paper sensitive to light
Film canister or soup can
Drill with drill bit
Scissors
Sunlight

The paper from a sun print kit has a very special coating that makes the paper react to light. Most sun print kits use set of light-sensitive chemicals such as potassium ferricyanide and ferric ammonium citrate to make a cyanotype solution. The paper changes color when exposed to UV light. In fact, you can try exposing the paper to different colors and see which changes the paper the most over a set amount of time!

The last step of this chemical process is to ‘set’ the reaction by washing it in plain water – this keeps the image on the paper so it doesn’t all disappear when you hang it on the wall. After the paper dries, the area exposed to UV light turns blue, and everything shaded turns white.

You can use sun print paper to test how well your sunblock works – just smear your favorite sunscreen over a sheet (or put a couple dabs of each kind) and see how well the paper stays protected: if it turns white, the light is getting through. If it stays blue, the sunscreen blocked the light!

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Thermometer

Wednesday June 29, 2011

First invented in the 1600s, thermometers measure temperature using a sensor (the bulb tip) and a scale. Temperature is a way of talking about, measuring, and comparing the thermal energy of objects. We use three different kinds of scales to measure temperature. Fahrenheit, Celsius, and Kelvin. (The fourth, Rankine, which is the absolute scale for Fahrenheit, is the one you’ll learn about in college.)

Mr. Fahrenheit, way back when (18th century) created a scale using a mercury thermometer to measure temperature. He marked 0° as the temperature ice melts in a tub of salt. (Ice melts at lower temperatures when it sits in salt. This is why we salt our driveways to get rid of ice). To standardize the higher point of his scale, he used the body temperature of his wife, 96°.

As you can tell, this wasn’t the most precise or useful measuring device. I can just imagine Mr. Fahrenheit, “Hmmm, something cold…something cold. I got it! Ice in salt. Good, okay there’s zero, excellent. Now, for something hot. Ummm, my wife! She always feels warm. Perfect, 96°. ” I hope he never tried to make a thermometer when she had a fever.

Just kidding, I’m sure he was very precise and careful, but it does seem kind of weird. Over time, the scale was made more precise and today body temperature is usually around 98.6°F.

Later, (still 18th century) Mr. Celsius came along and created his scale. He decided that he was going to use water as his standard. He chose the temperature that water freezes at as his 0° mark. He chose the temperature that water boils at as his 100° mark. From there, he put in 100 evenly spaced lines and a thermometer was born.

Last but not least Mr. Kelvin came along and wanted to create another scale. He said, I want my zero to be ZERO! So he chose absolute zero to be the zero on his scale.

Absolute zero is the theoretical temperature where molecules and atoms stop moving. They do not vibrate, jiggle or anything at absolute zero. In Celsius, absolute zero is -273 ° C. In Fahrenheit, absolute zero is -459°F (or 0°R). It doesn’t get colder than that!

As you can see, creating the temperature scales was really rather arbitrary:

“I think 0° is when water freezes with salt.”
“I think it’s just when water freezes.”
“Oh, yea, well I think it’s when atoms stop!”

Many of our measuring systems started rather arbitrarily and then, due to standardization over time, became the systems we use today. So that’s how temperature is measured, but what is temperature measuring?

Temperature is measuring thermal energy which is how fast the molecules in something are vibrating and moving. The higher the temperature something has, the faster the molecules are moving. Water at 34°F has molecules moving much more slowly than water at 150°F. Temperature is really a molecular speedometer.

Let’s make a quick thermometer so you can see how a thermometer actually works:

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Materials:

plastic bottle
straw
hot glue or clay
water
food coloring
rubbing alcohol
index card and pen

When something feels hot to you, the molecules in that something are moving very fast. When something feels cool to you, the molecules in that object aren’t moving quite so fast. Believe it or not, your body perceives how fast molecules are moving by how hot or cold something feels. Your body has a variety of antennae to detect energy. Your eyes perceive certain frequencies of electromagnetic waves as light. Your ears perceive certain frequencies of longitudinal waves as sound. Your skin, mouth and tongue can perceive thermal energy as hot or cold. What a magnificent energy sensing instrument you are!

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Hygrometer

Wednesday June 29, 2011

Hygrometers measure how much water is in the air, called humidity. If it's raining, it's 100% humidity. Deserts and arid climates have low humidity and dry skin. Humidity is very hard to measure accurately, but scientists have figured out ways to measure how much moisture is absorbed by measuring the change in temperature (as with a sling psychrometer), pressure, or change in electrical resistance (most common).

The dewpoint is the temperature when moist air hits the water vapor saturation point. If the temperature goes below this point, the water in the air will condense and you have fog. Pilots look for temperature and dewpoint in their weather reports to tell them if the airport is clear, or if it''s going to be 'socked in'. If the temperature stays above the dewpoint, then the airport will be clear enough to land by sight. However, if the temperature falls below the dewpoint, then they need to land by instruments, and this takes preparation ahead of time.

A sling psychrometer uses two thermometers (image above), side by side. By keeping one thermometer wet and the other dry, you can figure out the humidity using a humidity chart. Such as the one on page two of this document. The psychrometer works because it measures wet-bulb and dry-bulb temperatures by slinging the thermometers around your head. While this sounds like an odd thing to do, there's a little sock on the bottom end of one of the thermometers which gets dipped in water. When air flows over the wet sock, it measures the evaporation temperature, which is lower than the ambient temperature, measured by the dry thermometer.

Scientists use the difference between these two to figure out the relative humidity. For example, when there's no difference between the two, it's raining (which is 100% humidity). But when there's a 9^oC temperature difference between wet and dry bulb, the relative humidity is 44%. If there's 18^oC difference, then it's only 5% humidity.

You can even make your own by taping two identical thermometers to cardboard, leaving the ends exposed to the air. Wrap a wet piece of cloth or tissue around the end of one and use a fan to blow across both to see the temperature difference!

One of the most precise are chilled mirror dewpoint hygrometers, which uses a chilled mirror to detect condensation on the mirror's surface. The mirror's temperature is controlled to match the evaporation and condensation points of the water, and scientists use this temperature to figure out the humidity.

We're going to make a very simple hygrometer so you get the hand of how humidity can change daily. Be sure to check this instrument right before it rains. This is a good instrument to read once a day and log it in your weather data book.

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Materials:

single hair
index card
tack
cardboard
tape
scissors
dime

This device works because human hair changes length with humidity, albeit small. We magnify this change by using a lever arm (the arrow and mark the different places on the cardboard to indicate levels of humidity. Does all hair behave the same way? Does it matter if you use curly or straight hair, or even the color of the hair? Does gray work better than blonde?

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Anemometer

Wednesday June 29, 2011

Most weather stations have anemometers to measure wind speed or wind pressure. The kind of anemometer we’re going to make is the same one invented back in 1846 that measures wind speed. Most anemometers use three cups, which is not only more accurate but also responds to wind gusts more quickly than a four-cup model.

Some anemometers also have an aerovane attached, which enables scientists to get both speed and direction information. It looks like an airplane without wings – with a propeller at the front and a vane at the back.

Other amemometers don’t have any moving parts – instead they measure the resistance of a very short, thin piece of tungsten wire. (Resistance is how much a substance resists the flow of electrical current. Copper has a low electrical resistance, whereas rubber has a very high resistance.) Resistance changes with the material’s temperature, so the tungsten wire is heated and placed in the airflow. The wind flowing over the wire cools it down and increases the resistance of the wire, and scientists can figure out the wind speed.

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Scientists also use sonic anemometers, which use ultrasonic waves to detect wind speed. The great thing about sonic anemometers is that they can measure speed in all three directions, which is great for studying wind that is not all moving in the same direction (like gusts and hurricanes).

Sonic anemometers send a sound wave from one side to the other and measure the time it takes to travel. Which means that these can also be used as thermometers, as temperature will also change the speed of sound. Since there are no moving parts, you’ll find these types of anemometers in harsh conditions, like on a buoy or in the desert, where salt disintegrates and dust gets in the way of the cup-style anemometer. The big drawback to sonic anemometers is water (like dew or rain): if the transducers get wet, it changes the speed of sound and gives an error in the reading.

The quickest anemometer to make is to attach the end of a string (about 12″ long) to a ping pong ball. Suspend the string in the wind, like from a fan or hair dryer (use the ‘cool’ setting). Since the ball is so lightweight, it’s quite responsive to wind speed.

Add a protractor flipped upside down (so you can measure the angle of the string). Use the measurements below to figure out the wind speed. For example, mark the 90^o angle with “0 mph”. This is your ping pong ball at rest in no wind. Use the numbers below to make the rest:

Angle	Wind Speed
degrees	mph
90	0
80	8
70	12
60	15
50	18
40	21
30	26
20	33

Now let’s make a four-cup anemometer. Here’s what you need to do:

Materials:

four lightweight cups
two sticks or popsicle sticks
tape or hot glue
tack or pin
pencil with eraser on top
block of foam (optional)

How steady was the wind that you measured? If you place your anemometer next to a door or a window, is there wind? How fast? Where could you place your anemometer so you can quickly read it each day?

By making two anemometers, one that you already know what the wind speed is, you can easily figure out how to calibrate the other. For example, how fast do the cups fly around when the ping pong ball anemometer indicates 12 mph? Can you see each cup, or are they a blur? You’ll get a feel for how to read the four-cup model by eye once you’ve had practice.

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Barometer

Wednesday June 29, 2011

French physicist Blaise Pascal. He developed work on natural and applied sciences as well being a skilled mathematician and religious philosopher.

A barometer uses either a gas (like air) or a liquid (like water or mercury) to measure pressure of the atmosphere. Scientists use barometers a lot when they predict the weather, because it’s usually a very accurate way to predict quick changes in the weather.

Barometers have been around for centuries – the first one was in the 1640s!

At any given momen, you can tell how high you are above sea level by measure the pressure of the air. If you measure the pressure at sea level using a barometer, and then go up a thousand feet in an airplane, it will always indicate exactly 3.6 kPa lower than it did at sea level.

Scientists measure pressure in “kPa” which stands for “kilo-Pascals”. The standard pressure is 101.3 kPa at sea level, and 97.7 kPa 1,000 feet above sea level. In fact, every thousand feet you go up, pressure decreases by 4%. In airplanes, pilots use this fact to tell how high they are. For 2,000 feet, the standard pressure will be 94.2 kPa. However, if you’re in a low front, the sea level pressure reading might be 99.8 kPa, but 1000 feet up it will always read 3.6 kPa lower, or 96.2 kPa.

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Materials:

balloon
straw or stick
water glass or clean jam jar
index card
tape

At standard pressure, depending on the kind of barometer you have, you’ll find they all read one of these: 101.3 kPa; 760 mmHg (millimeters of mercury, or “torr”); 29.92 inHg (inches of mercury); 14.7 psi (pounds per square inch); 1013.25 millibars/hectopascal. They are all different unit systems that all say the same thing.

Just like you can have 1 dollar or four quarters or ten dimes or 20 nickels or a hundred pennies, it’s still the same thing.

Why does water boil differently at sea level than it does on a mountain top?

It takes longer to cook food at high altitude because water boils at a lower temperature. Water boils at 212^oF at standard atmospheric pressure. But at elevations higher than 3,500 feet, the boiling point of water is decreased.

The boiling point is defined when the temperature of the vapor pressure is equal to the atmospheric pressure. Think of vapor pressure as the pressure made by the water molecules hitting the inside of the container above the liquid level. But since the saucepan of water is not sealed, but rather open to the atmosphere, the vapor simply expands to the atmosphere and equals out. Since the pressure is lower on a mountaintop than at sea level, this pressure is lower, and hence the boiling point is lowered as well.

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Rain Gauge

Wednesday June 29, 2011

Also known as an udometer or pluviometer or ombrometer, or just plan old ‘rain cup’, this device will let you know how much water came down from the skies. Folks in India used bowls to record rainfall and used to estimate how many crops they would grow and thus how much tax to collect!

These devices reports in “millimeters of rain” or “”centimeters of rain” or even inches of rain”. Sometimes a weather station will collect the rain and send in a sample for testing levels of pollutants.

While collecting rain may seem simple and straightforward, it does have its challenges! Imagine trying to collect rainfall in high wind areas, like during a hurricane. There are other problems, like trying to detect tiny amounts of rainfall, which either stick to the side of the container or evaporate before they can be read on the instrument. And what happens if it rains and then the temperature drops below freezing, before you’ve had a chance to read your gauge? Rain gauges can also get clogged by snow, leaves, and bugs, not to mention used as a water source for birds.

So what’s a scientist to do?

Press onward, like all great scientists! And invent a type of rain gauge that will work for your area. We’re going to make a standard cylinder-type rain gauge, but I am sure you can figure out how to modify it into a weighing precipitation type (where you weigh the amount in the bottle instead of reading a scale on the side), or a tipping bucket type (where a funnel channels the rain to a see-saw that tips when it gets full with a set amount of water) , or even a buried-pit bucket (to keep the animals out).
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Materials:

two water bottles
scissors
rainy day (or use water)

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Extracting DNA in your Kitchen

Monday May 2, 2011

If the cell has a nucleus, the DNA is located in the nucleus. If not, it is found in the cytoplasm. DNA is the genetic material that has all the information about a cell.

DNA is a long molecule found in the formed by of two strands of genes. DNA carries two copies—two “alleles”—of each gene. Those alleles can either be similar to each other (homozygous), or dissimilar (heterozygous).

We’re going to learn how to extract DNA from any fruit or vegetable you have lying around the fridge. Are you ready?

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Materials:

pumpkin OR apple OR squash OR bananas OR carrots OR anything else you might have in the fridge
dishwashing detergent
91% isopropyl alcohol
coffee filter and a funnel (or use paper towels folded into quarters)
water
blender
clear glass cup

Download Student Worksheet & Exercises

Procedure:

Step 1: First, grab your fruit or vegetable and stick it in your blender with enough water to cover. Add a tablespoon of salt and blend until it looks well-mixed and like applesauce. Don’t over-blend, or you’ll also shred the DNA strands!

Step 2: Pour this into a bowl and mix in the detergent. Don’t add this in your mixer and blend or you’ll get a foamy surprise that’s a big mess. You’ll find that the dishwashing detergent and the salt help the process of breaking down the cell walls and dissolving the cell membranes so you can get at the DNA.

Step 3: Place a coffee filter cone into a funnel (or use a paper towel folded into quarters) and place this over a cup. Filter the mixture into the cup. When you’re done, simply throw away the coffee filter. Note: Keep the contents in the cup!

Step 4: Be careful with this step! You’ll very gently (no splashing!) pour a very small about of alcohol into the cup (like a tablespoon) so that the alcohol forms a layer above the puree.

Step 5: Observe! Grab your compound microscope and take a sample from the top. You’ll want a piece from the ghostly layer between the puree and the alcohol – this is your DNA.

What’s going on?

Veggies and fruits are made of water, cellulose, sugars, proteins, salts, and DNA. To get at the DNA, you first need to get inside the cells and separate it out from the other parts. The blender breaks up the fibers that hold the cells together.

The salt and detergent are added next so they can break down the cell walls. Cell walls of plants are made of cellulose. Inside that cellulose is another cell wall (cell membrane). This membrane has an outer later of sugar and an inner layer of fat.

The detergent is a special molecule that has an attraction to water and fats (which is why it works to get your dishes clean). The end of the molecule that is attracted to fat attaches to the fat part of the cell membrane. When you stir up the mixture, it breaks up the membrane (since the other end likes water). It wedges itself inside and opens the cell up… which causes the DNA to flow out.

Since DNA dissolves in water, it stays in the vegetable juice. When alcohols is added, the DNA “comes out” of solution as the ghostly white strands seen at the bottom of the alcohol layer.

For Advanced Students:

For advanced students, here’s a set of videos that detail the cell walls, the basic biological molecules, DNA and RNA and how everything works together.

First watch this video below to see how we broke down the cell walls in the DNA extraction experiment:

Here’s a video on how DNA and RNA work:

Here’s a video that describes how the four biological molecules (proteins, lipids, carbohydrates, and nucleic acids) work:

Exercises

What are fruits and veggies made of?
What does DNA stand for?
What is DNA?
What is a gene?
Describe the structure of DNA.

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Tracking Traits

Monday May 2, 2011

Why do families share similar features like eye and hair color? Why aren’t they exact clones of each other? These questions and many more will be answered as well look into the fascinating world of genetics!

Genetics asks which features are passed on from generation to generation in living things. It also tries to explain how those features are passed on (or not passed on). Which features are stay and leave depend on the genes of the organism and the environment the organism lives in. Genes are the “inheritance factors “described in Mendel’s laws. The genes are passed on from generation to generation and instruct the cell how to make proteins. A genotype refers to the genetic make-up of a trait, while phenotype refers to the physical manifestation of the trait.

We’re going to create a family using genetics!

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Materials
• Paper or use this Genetics Table
• Two different coins
• Scissors
• Glue or Tape

Download Student Worksheet & Exercises

Step one: Creating the Parent Generation

First you’re going to create the genetic make-up of the parents. Here’s how:
Take out the Genetics Data Table, and flip the first coin to create the genetic profile for the mother.
Flip the coin and in the Mother’s Hair trait column, write D for dominant if the coin reads heads, and R for recessive if tails in the table.
Flip the coin again. In the Mother’s Hair trait column right after the first trait, write D for dominant if the coin reads heads, and R for recessive if tails in the table.
If you flipped heads the first time and tails the second, you’d write “DR” in the Mother’s Hair box.
Continue this process for all of Mother’s traits. You should have two letters in each box for the entire column.
Repeat steps 3-6 for Father. When you’ve completely filled out Mother’s and Father’s columns, you’ve completed the paternal genetic profile. Now you’re ready for the next part:

Step two: The Child

Will the child be a boy or a girl? To determine this, flip the second coin. Heads for a boy, tails for a girl. After this is decided, circle boy or girl under “child 1” on the Genetics Data Table.
Now the first coin will represent the gene from the mother and the second coin will represent the gene from the father.
Start with the Hair trait: Flip both coins. If the first coin is tails, take the first trait from the mother. If the first coin is heads, take the second trait.
1. For example, if the first coin is tails, and the mother’s code is DR, then write “D” in the child one column for hair.
2. Do the same thing for the father’s traits with the second coin. For example, if the second coin is heads, and the father’s code is DR, then write “R” in the Hair Trait column of child 1.
3. By the end of this step, child 1 should have one letter from the mother, and one letter for the father in child 1’s hair trait column.
Use the same steps used to find the genetic code for the hair trait to find the code for the rest of the traits. By the end all the traits should have one letter from the mother’s genetic code and one letter from the father’s genetic code.

Step 3: What the Child Looks Like

Grab a sheet of paper and start drawing the child. If the genetic code for a trait has a “D” in it, then the dominant trait is used.

For example, if the hair color is DD, DR, or RD then the hair color is dark. If the hair color code is RR, then the hair color is light. Draw the traits on your paper!

You can repeat this for as many children as you would like in your family.

Step 4: Make another family and compare!

Are all families alike? What if you try this process again for another family? Do you see any similarities or differences? Do similar features come from dominant genes? Do differences come from recessive genes? What other traits would you include? Write this in your science journal!

Conclusions:

In fact, most similarities should come from the dominant genes because they are expressed more often. The recessive genes are expressed less often, so the create the differences.

Extra credit:

What percent of the children expressed the dominant allele of each trait? Did you get Mendel’s results? Do the calculations and check it out!

Exercises

What is the difference between a genotype and a phenotype?
What is a dominant trait?
What is a recessive trait?
Assume B=Black hair and b=blond hair. Make a Punnet square to cross Bb with bb. Tell what the possibilities are for offspring hair color.
Why don’t traits simply average out in offspring. For example, why does a tall plant crossed with a short plant not yield a bunch of average-sized plants?
In your activity, what percent of the children expressed the dominant allele of each trait? Did you get Mendel’s results? Do the calculations and check it out!

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Family Pedigree

Monday May 2, 2011

A pedigree analysis chart, usually used for families, allow us to visualize the inheritance of genotypes and phenotypes (traits). In this chart, the P, F1, and F2 generation are represented by the numerals I, II, and III respectively. Notice that those carrying the trait are colored red, and those not carrying the trait (the normal-looking ones) are in blue. The normal, non-trait carrying organisms on the chart are called the wild-type.

The term wild-type is used in genetics often to refer to organisms not carrying the trait being studied. For example, if we were studying a gene that turns house-flies orange, we would call the normal-looking ones the wild-type.

Let’s make a pedigree for your family. Here’s what you need:

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Materials:
• Paper
• Pen
• Access to a photocopier (optional)

To start this project, draw a pedigree showing the different members of your family.

a. Include as many family members as you can get data from. The more people and generations you include, the more likely it is that you’ll have enough information to determine the mode of inheritance.

b. You might need help from your parents to figure out all the relationships.

2. If you have access to a photocopier, make four copies of the pedigree—one for each trait you are going to evaluate. If photocopying isn’t an option, manually copy the pedigree.

3. Determine the phenotype of each person on your pedigree for each of the four traits. Use a separate pedigree for each trait. Examples are: eye-color, hair color, widow’s peak, height. Note: Widow’s peak can vary considerably; score any sort of V-shaped hairline as positive.

4. From your pedigrees, can you deduce the mode of inheritance for each trait? For which traits is your pedigree informative? If you don’t have enough information to determine the mode of inheritance of a particular trait, try making a pedigree for another family.

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Cell in Action

Monday May 2, 2011

Cells make up every living thing. Take a look at all the living things you can see just in your house. You can start off with you and your family. If you have any pets, be sure to include them. Don’t forget about houseplants as well – they’re alive. Now take a walk outside. You’ll likely see many more plants, as well as animals like birds and insects. Now imagine if all those living things were gone. That’s how it would be if there were no cells, because cells are what all those living things are made of.

Animals, plants and other living things look different, and contain many different kinds of cells, but when you get down to it, all of us are just a bunch of cells – and that makes cells pretty much the most important thing when it comes to life!

Here’s a video on the difference between animal and plant cells:

Are you wondering what all the different organelles are inside the cell? Here’s a video that goes into all the cool detail (note – this video is more for advanced students):

Now pull out your science journal! As you watch this video below, write down the organelles you see and describe what you think is happening.

What’s going on?

The endoplasmic reticulum, shown in red, transports proteins to the Golgi Apparatus, shown in blue. The Golgi Apparatus packages proteins and sends them where they are needed, either in the cell, or to the cell membrane for transport out of the cell.

Protozoa in the Grass

Monday May 2, 2011

This experiment allows you to see protozoa, tiny-single celled organisms, in your compound microscope. While I can go in my backyard and find a lot of interesting pond scum and dead insects, I realize that not everybody has a thriving ecosystem on hand, especially if you live in a city.

I am going to show you how to grow a protozoa habitat that you can keep in a window for months (or longer!) using a couple of simple ingredients.

Once you have a protist farm is up and running, you’ll be able to view a sample with your compound microscope. If you don’t know how to prepare a wet mount or a heat fix, you’ll want to review the microscope lessons here.

Protozoa are protists with animal-like behaviors. Protists live in almost any liquid water environment. Some protists are vital to the ecosystem while others are deadly.

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Download Student Worksheet & Exercises

Here’s how you can grow your own to look at under a compound microscope:

1. Leave a glass of water out overnight, to get rid of chlorine. If you are in a hurry, use filtered water (not distilled) instead.

2. Add dead grass to the glass of water. Stir.

3. Add yeast to the glass. Stir again.

4. Allow the glass to sit overnight in a warm place. For best results, let grow and ferment for several weeks.

5. Each day for a week, observe a sample of water and/or grass under the microscope, after the first 24 hours.

6. Sketch the protozoa you see, and note if there are more or less of a certain type as time goes on in your science journal.

Exercises

What is a cell?
Why are cells so small?
What is a protozoa?
How does it develop?

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Celery Stalk Water Race

Monday May 2, 2011

If you think of celery as being a bundle of thin straws, then it’s easy to see how this experiment works. In this activity, you will get water to creep up through the plant tissue (the celery stalk) and find out how to make it go faster and slower.

The part of the celery we eat is the stalk of the plant. Plant stalks are designed to carry water to the leaves, where they are needed for the plant to survive. The water travels up the celery as it would travel up any plant.

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Download Student Worksheet & Exercises

1. First, find four celery stalks about the same size with leaves still attached.

2. Mix up a four-cup batch of colored water (try purple).

3. Place your celery stalks in the water, leaf-end up. After an hour or two, take it out and place it on the paper towel. Label your celery stalk with the each time length it was in the water.

4. Repeat this for different increments of time. Try one overnight!

5. Use a ruler and measure how high the water went. Record this in your science journal.

6. Now make a graph that compares the time to distance traveled by placing the time on the horizontal axis and the distance traveled on the vertical.

7. What happens if you start with hot water? Ice cold water? Salt water?

8. What happens if you cut the celery stalk at the base high enough so it straddles two cups of different colors?

Exercises

What two types of transport move substances into a cell?
How does water get into the celery?
What are the tubes in celery called?
In what direction does air flow? Hint: Think of the balloon example.
What happens to the water after it travels through a plant?
Use answers 1-4 to describe the process of water traveling through a celery stalk.

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Bacteria in Humans and Dogs

Monday May 2, 2011

Some organisms, like bacteria, consist of only one cell. Other organisms, like humans, consist of trillions of specialized cells working together. Even if organisms look very different from each other, if you look close enough you’ll see that their cells have much in common.

Most cells are so tiny that you can’t see them without the help of a microscope. The microscopes that students typically use at school are light microscopes.

Robert Hooke created a primitive light microscope in 1665 and observed cells for the very first time. Although the light microscope opened our eyes to the existence of cells, they are not useful for looking at the tiniest components of cells. Many structures in the cell are too small to see with a light microscope.
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In this experiment, you will get to observe single-celled organisms (bacteria, actually) that live in the mouths of both humans and dogs using your compound microscope.

1. You’ll need to get your materials together. Be sure to label the Petri dishes and have your other equipment out: the cotton swabs, the canine volunteers and the human volunteers.

2. First, scrape the inside of a volunteer’s cheek use the cotton tip to swab. Swirl the cotton swab onto a Petri dish.

3. Repeat this for the rest of your human and dog volunteers.

4. Find a dark, warm spot for your Petri dishes to live in that won’t be disturbed for at least 24 hours.

5. After a day, remove the Petri dishes and place it next to your compound microscope.

6. Use a fresh swab to move the bacteria from the Petri dish to the slide and use a staining technique (covered in the Microscope Lab).

7. View each of your specimens, recording everything as you go along.

8. So what do you think? Whose mouth is cleaner – dogs or people?

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Osmosis in Potatoes & Beans

Monday May 2, 2011

One way substances can get into a cell is called passive transport. One special kind of passive transport is osmosis, when water crosses into the cell. This experiment allows you to see the process of osmosis in action. Are you ready?

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Download Student Worksheet & Exercises

1. Cut two thin slices of potato. The pieces should be about the same thickness and be slightly flimsy.

2. Place both slices in separate glasses of water.

3. Add salt to one of the glasses.

4. Wait about 15 minutes.

5. Pull out the two pieces of potato and make observations in our science journal.

Did you notice that the potato slice in the fresh water became a little stiffer, while the potato in salt water became rather flimsy? Remember that cells are made of water, and that the water in the cells flows from areas of low salt concentration to high salt concentration. That means that if the water outside the cell is saltier than the water inside, water will move from the inside of the cell to the outside. As the water left the cell it was like letting the air out of a balloon. As more and more of the cells lost water, the slice of potato became soft and flexible. If the water inside was saltier, the opposite happens, and some water goes into the cells, stiffening them up.

Osmosis is the diffusion of water molecules through a membrane, where the water molecules move from high water concentration to areas of low water concentration.

Salt starts osmosis by attracting water and causing the water to move toward and across the membrane. Remember that salt is a solute, and when water is added to a solute, it spreads out (diffuses) the concentration of salt, and that creates a chemical solution.

Imagine the salt concentration inside a cell being the exact same as the salt concentration outside the cell – what would happen? Right – the water level will stay the same and nothing would happen. Now imagine there’s more salt inside of a cell than outside it. What happens now? The water moves through the membrane into the cell causing it to swell with water.

If the cell is placed in a higher concentration of salt (like sticking a carrot in a salt bath), the water will leave the cell, and that’s why the plant cells shrink and wilt. This is also why salt kills plants, because it takes water from the cells. This doesn’t just happen in plants, though. Animals can also get dehydrated if they drink ocean water.

Questions to Ask:

How was the concentration of salt different in each cup?
Which direction was water flowing in each cup?
Why did one potato become stiff, while the other became flimsy?

Let’s do this experiment again, but use beans instead of potatoes.

1. Place enough beans and water in a glass to completely fill it

2. Place the glass on a cookie sheet

3. Leave the glass alone for several hours… even overnight!

4. While you wait, take out your science journal and write about what you expect to happen. When your experiment is ready, record what you found.

Questions to Ask:
1. The beans should begin to fall out of the water. If you look at them, you will see that they have expanded. What happened?

2. Where was the concentration of water greater – inside or outside of the beans? Explain.

Exercises

For Potatoes

How was the concentration of salt different in each cup?
Which direction was water flowing in each cup?
Why did one potato become stiff, while the other became flimsy?

For Beans

If you look at the beans, you will see that they have expanded. What happened?
Where was the concentration of water greater – inside or outside of the beans? Explain.

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Carbon Dioxide and Photosynthesis

Monday May 2, 2011

Photosynthesis is a process where light energy is changed into chemical energy. As we said in the last section, this process happens in the chloroplast of plant cells. Photosynthesis is one of the most important things that happen in cells.

In fact, photosynthesis is considered one of the most important processes for all life on Earth. It makes sense that photosynthesis is really important to plants, since it gives them energy, but why is it so important to animals? Let’s learn a little more about photosynthesis and see if we can answer that question.

There are many steps to photosynthesis, but if we wanted to sum it up in one equation, it would be carbon dioxide (CO₂) + water (H₂O) makes glucose (C₆H₁₂O₆) and oxygen (O₂). These words can be written like this:

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6CO₂ + 6H₂O + Light Energy –> C₆H₁₂O₆+ 6O₂

Carbon dioxide, water, and energy combine to form glucose and oxygen.

We learned in the last section that glucose is a kind of sugar. This sugar is important for energy, so the plant stores all the glucose it creates. However, the plant releases the oxygen it creates.

Now we can see two reasons why photosynthesis is so important not just to plants, but to animals too. First, all animals need oxygen to live. Photosynthesis produces oxygen, so without this process, animals could not survive. Also, don’t forget that since animals can’t make their own food, they have to eat plants, or eat other animals that have eaten plants. So without plants, animals would quickly run out of food.

This experiment will demonstrate that carbon dioxide is necessary in photosynthesis.

Materials:

candle
lighter with adult help
large glass jar
stopwatch
leafy plant (weeds work also)

Optional: sodium hydroxide and iodine

Download Student Worksheet & Exercises

1.Light your candle. invert the glass over it and time how long it takes the candle to use up all the oxygen and extinguish itself. Write this number down in your journal.

2. Find a young plant or bush, preferably with a lot of growth and leaves. Place your candle next to the plant (don’t burn your plant!) and invert the jar over it again. Use your stopwatch to time how long the candle stays lit. Write this number down in your journal.

3. Which one do you expect to take longer? What actually happened?

OPTIONAL BUT DANGEROUS…

Place the caustic soda on a disposable plate. Don’t get this on your hands or eyes – it’s very corrosive. Handle this chemical ONLY with gloves and keep away from small children and pets like dogs and cats.

Place the caustic soda next to the plant and cover with the glass. Leave this setup undisturbed for a few hours. When you’re done, take a leaf from the plant and do an iodine test on it to find out if there is starch present. Simply place a drop of iodine on the leaf. Iodine changes to dark blue when starch is present.

Exercises

Describe the process of photosynthesis in words.
Write the chemical equation for photosynthesis.
What is glucose?
Why is glucose important for plants?
Why are plants necessary for animals?
Does the result of the experiment depend on how large the plant is? Why or why not?

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Onion Mitosis

Monday May 2, 2011

In eukaryotes there is a nucleus, so a more complex process called mitosis is needed with cell division. Mitosis is divided into four parts, or phases:

Phase 1 – Prophase: In this phase the nuclear membrane begins to break down and the DNA forms structures called chromosomes.

Phase 2 – Metaphase: In this phase the chromosomes line up along the center of the parent cell

Phase 3 – Anaphase: In this phase, the chromosomes break apart, with a complete set of DNA going to each side of the cell

Phase 4 – Telophase: In this phase, a new nuclear membrane forms around each of the sets of DNA

The four stages of mitosis (the cell at the top has not started mitosis) lead to two daughter cells.

A little after telophase, the cytoplasm splits and a new cell membrane forms. Once again, two daughter cells have formed. Take a look at this animation for a good overview of mitosis and see if you can identify all the phases.

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Cells continue to divide until a protein tells them to stop. As they divide, they become different and specialized, eventually making the tissues and organs found in the many different living things we see every day.

Download Student Worksheet & Exercises

Mitosis is part of the cell cycle, a larger process that living organisms use to repair damage, grow, or just maintain condition. In this experiment, we’re going to figure out the time it takes for a cell to go through each of the four mitosis states.

Grab your science journal and here’s what you do:

Materials:

Compound microscope with slides and coverslip
Onion (the root tip, not the onion itself) – you can grow your own if you can’t find any at the store (see image at above left). Place the bottom of an onion in a glass of water for a couple of days and you’ll see the roots grow to the size you need (about 2 cm long).
Science journal

First, set up your microscope.

Next, prepare an onion sample. Take it from the root tip called the meristematic zone (use the picture on the right), just above the root cap at the very end of the tip.

Use the staining technique we show in our Microscope Lab. Cut the sample lengthwise before placing it on the slide.

If you want to stop the cell division process while you watch the slide, you’ll need to prepare a heat fix mount instead (make sure you don’t boil the liquid when you use the candle or you’ll ruin your slide). You can add a drop or two of stain after the heat fix and blot the excess with a paper towel. Add a drop of water and a coverslip and you’re ready to look!

Try different powers of magnification to find the four different stages of mitosis. Count the number of cells found at each stage of mitosis and figure out the percentage. (Total up the number of cells and use this number to divide each count by. Don’t forget to multiply by 100 for percentage!)

Out of all four stages of mitosis, which one takes the most time to complete? The shortest time? What happens to the process if we skip metaphase?

Exercises

What is mitosis?
What are the four stages of mitosis? Briefly describe what happens in each.
Out of all four stages of mitosis, which one takes the most time to complete? The shortest time? What happens to the process if we skip metaphase?

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Cool Carrot Osmosis

Monday May 2, 2011

The carrot itself is a type of root—it is responsible for conducting water from the soil to the plant. The carrot is made of cells. Cells are mostly water, but they are filled with other substances too (organelles, the nucleus, etc).

We’re going to do two experiments on a carrot: first we’re going to figure out how to move water into the cells of a carrot. Second, we’ll look at how to move water within the carrot and trace it. Last, we’ll learn how to get water to move out of the carrot. And all this has to do with cells!

[am4show have=’p8;p9;p26;p53;p86;p87;’ guest_error=’Guest error message’ user_error=’User error message’ ]

Osmosis is how water moves through a membrane. A carrot is made up of cells surrounded by cell membranes. The cell membrane’s job is to keep the cell parts protected. Water can pass through the membrane, but most things can’t.

And water always moves through cell membranes towards higher chemical concentrations. For example, a carrot sitting in salt water causes the water to move into the salty water. The water moves because it’s trying to equalize the amount of water on both the inside and outside of the membrane. The act of salt will draw water out of the carrot, and as more cells lose water, the carrot becomes soft and flexible instead of crunchy and stiff.

You can reverse this process by sticking the carrot into fresh water. The water in the cup can diffuse through the membrane and into the carrot’s cells. If you tie a string around the carrot, you’ll be able to see the effect more clearly! Here’s what you do:

Download Student Worksheet & Exercises

Experiment #1: Water moving INTO the carrot via osmosis and UP the carrot.

In this experiment we will see the absorption of water by a carrot. Make note of differences between the carrot before the experiment, and the carrot afterward.

Materials

2 carrots
Sharp knife (be careful!)
Cutting board
Glass
Water
Food coloring

Procedure :

Step 1: Cut the tip off of a carrot (with adult supervision).

Step 2: Place the carrot in a glass half full of water

Step 3: Place the carrot somewhere where it can get some sunshine.

Step 4: Observe the carrot over several days.

What’s going on?

When surrounded by pure water, the concentration of water outside the carrot cells is greater than the concentration inside. Osmosis makes water move from greater concentrations to lesser concentrations. This is why the carrot grows in size—it fills with water!

Procedure:

Step 1: Re-do the four steps above in a new cup, and this time put several (10-12) drops of food coloring into the water.

Step 2: With the help of an adult, cut the carrot in half length-wise.

What’s going on?

Carrots are roots. They conduct water from the soil to the plant. If we were to repeat this experiment several times—first cutting the carrot at half a day, then one day, then one day and a half, etc—we would see the movement of the water up the root.

Experiment #2: Water moving OUT of the carrot via osmosis

In this experiment we answer the question “what if the concentration of water is greater inside the carrot?”

Materials

Large carrot
3 tablespoons of salt
Two glasses
String
water

Procedure

Step 1: Snap the carrot in half and tie a piece of string around each piece of carrot (make sure they’re tied tightly).

Step 2: Place each half in a glass half full of warm water.

Step 3: In one of the glasses, dissolve the salt.

Step 4: Leave overnight.

Step 5: The next morning pull on the strings. What do you observe?

What’s going on?

The salt-water carrot shrunk while the non-salt-water carrot bloated!

This is because of osmosis. Carrots are made up of cells. Cells are full of water. When the concentration of water outside the cell is greater than the concentration of water inside the cell, the water flows into the cell. This is why the non-salt-water carrot bloated—the concentration was greater outside the cell than inside. The concentration of water was greater inside the salt-water carrot than outside (because there was so much salt!) so the water flowed out of the cell. This made the salt-water carrot shrink.

Questions to Ask:

What happens if you try different vegetables besides carrots?
How do you think this relates to people? Do we really need to drink 8 glasses of water a day?
What happens (on the osmosis scale) if humans don’t drink water?
Use your compound microscope to look at a sample and draw the cells (both before and after taking a bath in the solution) in your science journal.
What did you expect to happen to the string? What really happened to the string?
Which solution made the carrot rubbery? Why?
Did you notice a change in the cell size, shape, or other feature when soaked in salt water? (Check your journal!)
Why did we bother tying a string? Would a rubber band have worked?
What would happen to a surfer who spent all day in the ocean without drinking water?
What do you expect to happen to human blood cells if they were placed in a beaker of salt water?

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Classifying Objects

Monday May 2, 2011

Grab a handful of buttons. Make sure there are all different kinds and colors.

If you don’t have buttons, use any pile of objects, like matchbox cars, coins, nuts, etc.

Now group the buttons according to size, color, texture, number of holes, shape, etc.

You can do this activity with shells, peanuts, plant leaves, or the back of your desk drawer. Is it easier to organize the non-living or the living things?

Membranes

Monday May 2, 2011

Here’s a fun experiment that shows you how much stuff can pass through a membrane. Scientist call it the semi-permeability of membranes.

Before we start, take out your science journal and answer this question: What do you think will happen when we stick a piece of celery into a glass of regular water. Anything special?

What if we add a teaspoon of salt to the water? Now do you think anything will happen?
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Let’s find out. First, you’ll need:

2 pieces of celery stalk
salt
2 glasses
a sensitive scale to weigh the celery

Note: If you don’t have a scale, you can rig up a balance by suspending two cups from a either end of of a pencil. Balance the center on a point (like another pencil) and you’ll be able to tell which is heavier at the end of this experiment (see image below).

You’ll need to measure the celery both before and after this experiment since you won’t be able to “read” the weight.

Trim your celery to be the same weight before you start your experiment.

Download Student Worksheet & Exercises

First, weigh the celery (both pieces) and record this in your journal.
Next, make your hypotonic solution (plain water). Fill a glass with water and stick your celery in for ten minutes.
Remove the piece of celery and pat dry. Weight it again and record your results. If you don’t see a weight difference, dip it in again for ten more minutes. Pat dry and weigh again.
Now make your hypertonic solution (salt water). Add a small amount of salt to the water (keep adding until no more can be dissolved and a small amount remains on the bottom).
Weight the second celery stalk and record it in your journal. Add this new celery stalk to the water. Wait impatiently for ten minutes. Remove and record the weight. Did you notice a difference? (Note – if you left the first one in for 20 minutes, make sure to leave this one in for the same amount of time.)

What effect did the salt solution have on the celery? Did it change in appearance? Did it feel different? Record your results in your journal!

Osmosis is the diffusion of water molecules through a membrane, where the water molecules move from high water concentration to areas of low water concentration.

If the cell is placed in a higher concentration of salt (like sticking a carrot in a salt bath), the water will leave the cell, and that’s why the plant cells shrink and wilt. This is also why salt kills plants, becaise it takes water from the cells. This doesn’t just happen in plants, though. Animals can also get dehydrated if they drink ocean water.

Exercises

In what direction does water move?
What is the process by which water crosses membranes by itself?
What are all living things made of?
Did the celery in the fresh water weigh more or less? Why?
Did the celery in the salt water weigh more or less after a few minutes?

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Newton’s First Law of Motion

Sunday May 1, 2011

First Law of Motion: Objects in motion tend to stay in motion unless acted upon by an external force. Force is a push or a pull, like pulling a wagon or pushing a car. Gravity is a force that attracts things to one another. Gravity accelerates all things equally. Which means all things speed up the same amount as they fall.

Materials: ball [am4show have='p8;p9;p10;p37;p72;p92;' guest_error='Guest error message' user_error='User error message' ]

What happens when you kick a soccer ball? The ‘kick’ is your external force. The ball will continue in a straight line as long as it can, until air drag, rolling resistance, and gravity cause it to stop.

Find out more about this key principle in Unit 1 and Unit 2.

Download Student Worksheet & Exercises

Exercises

What is inertia?
What is Newton’s First Law?
Will a lighter or heavier race car with the same engine win a short-distance race (like the quarter-mile)?

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Newton’s Second Law of Motion

Sunday May 1, 2011

Second Law of Motion: Momentum is conserved. Momentum can be defined as mass in motion. Something must be moving to have momentum. Momentum is how hard it is to get something to stop or to change directions. A moving train has a whole lot of momentum. A moving ping pong ball does not. You can easily stop a ping pong ball, even at high speeds. It is difficult, however, to stop a train even at low speeds.

Materials: garden hose connected to a water faucet

[am4show have='p8;p9;p10;p37;p72;p92;' guest_error='Guest error message' user_error='User error message' ] Place your thumb partway over the end of a garden hose. The water shoots out faster because the same amount of “stuff” has to pass through the exit. When the exit area decreases, less mass can pass through at one time, so the velocity increases.

Mathematically, momentum is mass times velocity, or Momentum=mv.

One of the basic laws of the universe is the conservation of momentum. When objects smack into each other, the momentum that both objects have after the collision, is equal to the amount of momentum the objects had before the crash.

The next video shows you how once the two balls hit the ground, all the larger ball’s momentum transferred to the smaller ball (plus the smaller ball had its own momentum, too!) and thus the smaller ball goes zooming to the sky.

Download Student Worksheet & Exercises

Do you see how using a massive object as the lower ball works to your advantage here? What if you shrink the smaller ball even more, to say bouncy-ball size? Momentum is mass times by velocity, and since you aren’t going to change the velocity much (unless you try this from the roof, which has its own issues), it’s the mass that you can really play around with to get the biggest change in your results. So for momentum to be conserved, after impact, the top ball had to have a much greater velocity to compensate for the lower ball ’s velocity going to zero.

Find out more about this key principle in Unit 1 and Unit 2.

Advanced students: Download your Momentum lab here.

Exercises

What concept does Newton’s Second Law of Motion deal with?
What is momentum?

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Newton’s Third Law of Motion

Sunday May 1, 2011

Third Law of Motion: For every action, there is an equal and opposite reaction.

Force is a push or a pull, like pulling a wagon or pushing a car. Gravity is a force that attracts things to one another. Weight is a measure of how much gravity is pulling on an object.

Gravity accelerates all things equally. Which means all things speed up (accelerate) the same amount as they fall. Acceleration is the rate of change in velocity. In other words, how fast is a change in speed and/or a change in direction happening.

Materials: balloon [am4show have='p8;p9;p10;p37;p109;p72;p92;' guest_error='Guest error message' user_error='User error message' ] Hold a balloon between your fingers and let go. Which way does the air inside the balloon travel relative to the balloon itself?

Answer: The balloon travels to the right and the air inside the balloon (at least initially) travels to the left.

Find out more about this key principle in Unit 1 and Unit 2.

Download Student Worksheet & Exercises

Exercises

What is Newton’s Third Law?
Give three examples of forces in pairs.
A rope is attached to a wall. You pick up the rope and pull with all you’ve got. A scientist walks by and adds a force meter to the rope and measures you’re pulling with 50 Newtons. How much force does the wall experience?
Can rockets travel in space if there’s nothing to push off of? Explain your answer.

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Maxwell’s First Equation

Sunday May 1, 2011

Maxwell’s First Equation: Like charges repel; opposites attract. The proton has a positive charge, the neutron has no charge (neutron, neutral get it?) and the electron has a negative charge. These charges repel and attract one another kind of like magnets repel or attract. Like charges repel (push away) one another and unlike charges attract one another. Generally things are neutrally charged. They aren’t very positive or negative, rather have a balance of both.

Materials: balloon

[am4show have=’p8;p9;p10;p37;p92;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Rub your head with a balloon and hold the charged balloon near your head so that your hair sticks to the balloon. Is there glue on the balloon? Why does your hair stick to the balloon?

Answer: The positively charged hair sticks to the negatively charged balloon.

Find out more about this key principle in Unit 10.

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Maxwell’s Second Equation

Sunday May 1, 2011

Maxwell’s Second Equation: All magnets have two poles. Magnets are called dipolar which means they have two poles. The two poles of a magnet are called north and south poles. The magnetic field comes from a north pole and goes to a south pole. Opposite poles will attract one another. Like poles will repel one another.

Materials: magnet you can break or cut in half, scissors or hammer (depending on the size of your magnet)

[am4show have=’p8;p9;p10;p37;p77;p92;’ guest_error=’Guest error message’ user_error=’User error message’ ]
What happens if you cut (or break) a magnet in half? The new magnets will each sport their own North-South poles!

Find out more about this key principle in Unit 10.

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Maxwell’s Third Equation

Sunday May 1, 2011

Maxwell’s Third Equation: Invisible magnetic fields exert forces on magnets AND invisible electrical fields exert forces on objects. A field is an area around a electrical, magnetic or gravitational source that will create a force on another electrical, magnetic or gravitational source that comes within the reach of the field. In fields, the closer something gets to the source of the field, the stronger the force of the field gets. This is called the inverse square law.

Materials: balloon, magnet, small objects like paper clips or iron filings

[am4show have=’p8;p9;p10;p37;p92;’ guest_error=’Guest error message’ user_error=’User error message’ ]

To see how magnetic fields exert forces, play with a couple of magnets or place a magnet in a test tube and then in a bed of iron filings. Do you see the magnetic field? If you don’t have iron filings, try noticing where on the magnet paper clips attach. Can you figure out where the lines of force occur?

Now let’s take a look at invisible electric fields. Notice how your hair sticks up when you build up a static electrical charge. You can build up a charge on dry days by scuffing along the carpet in socks, rubbing your hair with a balloon, sliding down a plastic slide, or by rubbing a fluorescent bulb with a wool sweater or plastic bag. Bring these charged items next to a pile of paper shreds or packing peanuts (or even a ping pong ball on a smooth, flat surface) and you’ll find the objects follow the charged object when placed near an electrical field.

Find out more about this key principle in Unit 10.

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Maxwell’s Fourth Equation

Sunday May 1, 2011

Maxwell’s Fourth Equation: Moving electrical charges (fields) generate magnetic fields AND changing magnetic fields generate electrical fields (electricity). We’re going to do a couple of experiments to illustrate both of these concepts.

Magnetic fields are created by electrons moving in the same direction. A magnetic field must come from a north pole of a magnet and go to a south pole of a magnet (or atoms that have turned to the magnetic field.) Iron and a few other types of atoms will turn to align themselves with the magnetic field. Compasses turn with the force of the magnetic field.

If an object is filled with atoms that have an abundance of electrons spinning in the same direction, and if those atoms are lined up in the same direction, that object will have a magnetic force.

Materials: magnet wire, nail, magnet, compass, 12VDC motor, bi-polar LED, D-cell battery, sandpaper

[am4show have=’p8;p9;p10;p37;p92;’ guest_error=’Guest error message’ user_error=’User error message’ ]

Wrap wire around a nail and connect to power to create a simple electromagnet that can pick up paper clips.

Or you can make a galvanometer: wrap your wire around a toilet paper tube and remove the tube after you’ve got 30+ turns of wire around it. Hook up the ends of the wire to a battery and place a compass through the middle of the coil. The needle should move when you energize the coil!

Connect a standard LED to the terminals of a 12DC motor and give the shaft a spin. The LED will light up! Why is that? There is a permanent magnet and an electromagnet (coil of wire) inside the motor. When you spin the shaft, you are essentially waving a permanent magnet past the coil of wire. The two ends of the coil wire are connected to the motor terminals, which are connected to the LED. You have just made an electric generator.

A “going further” experiment: You can make a second galvanometer and connect it to your first one, and then wave a magnet through the inside of one of the coils and watch the compass move inside the other! What’s going on here? The same as previously, only this time the magnet is being passed through (back and forth) one coil, which generates electricity in the wire and powers the second coil and turns the second coil into a magnet (as indicated my movement with the compass near the second coil).

How does this work? Since many electrons are moving in one direction, you get a magnetic field! The nail helps to focus the field and strengthen it. In fact, if you could see the atoms inside the nail, you would be able to see them turn to align themselves with the magnetic field created by the electrons moving through the wire.

Find out more about this key principle in Unit 10.

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Wave-Particle Duality of Light

Sunday May 1, 2011

Light acts like both a particle and a wave, but never both at the same time. But you need both of these concepts in order to fully describe how light works.

Energy can take one of two forms: matter and light (called electromagnetic radiation). Light is energy in the form of either a particle (like a marble) or a wave that can travel through space and some kinds of matter (like a wave on the ocean). You really can’t separate the two because they actually complement each other.

Low electromagnetic radiation (called radio waves) can have wavelengths longer than a football field, while high energy (gamma rays) can destroy living tissue. Light has wavelength (color), intensity (brightness), polarization (the direction of the waves that make up the light), and phase.

Materials: sink or bowl of water, glow in the dark toy, camera flash or sunlight

[am4show have=’p8;p9;p10;p37;p89;’ guest_error=’Guest error message’ user_error=’User error message’ ]

To show how light acts like a wave, you can pass light through a glass of water and watch the rainbow reflections on the wall. Why does this happen? When the light passes through the glass and the water, it changes wavelength and angle to give different frequencies of light (different colors).

Dip your fingers in a bathtub of water. Can you see the ripples traveling along the top surface? Light travels just like the waves on the surface of the water.

Light also acts like a particle. Use a camera flash to quickly charge a glow-in-the-dark toy in a dark closet. The light particles (photons) hit the electrons in the toy and transfer energy to the electron. The result is that the electron emits another light particle of a different wavelength, which is why glow-in-the-dark toys don’t reflect back the same color light they were charged with.

Learn more about this scientific principle in Unit 9.

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Mass is Conserved

Sunday May 1, 2011

A fundamental concept in science is that mass is always conserved. Mass is a measure of how much matter (how many atoms) make up an object. Mass cannot be created or destroyed, it can only change form.

Materials: paper, lighter or matches with adult help

[am4show have=’p8;p9;p10;p37;p91;’ guest_error=’Guest error message’ user_error=’User error message’ ]

When you eat a banana, the matter is converted into energy. Ignite a sheet of paper and the paper molecules combine with oxygen through a chemical change and turn into smoke and ash.

Learn more about this concept in Unit 3.

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First Law of Thermodynamics

Sunday May 1, 2011

First Law of Thermodynamics: Energy is conserved. Energy is the ability to do work. Work is moving something against a force over a distance. Force is a push or a pull, like pulling a wagon or pushing a car. Energy cannot be created or destroyed, but can be transformed.

Materials: ball, string

[am4show have=’p8;p9;p10;p37;p88;’ guest_error=’Guest error message’ user_error=’User error message’ ]

Roll a ball down a hill. The amount of energy the ball had while at rest at the top of the hill (potential energy) turns into kinetic energy while it zips to the bottom.

You can also swing on a swing and see this effect happen over and over again: when you’re at the highest point of your swing, you have the highest potential energy but zero kinetic energy (your speed momentarily goes to zero as you change direction). At the lowest point of your swing (when you’re moving the fastest), all your potential energy has turned into kinetic energy. Why do you eventually stop? The reason you eventually slow down and stop instead of swinging back and forth forever is that you have air resistance and friction where the chain is suspended from the bar.

Learn more about this scientific principle in Unit 4 and Unit 5 and Unit 13.
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Second Law of Thermodynamics

Sunday May 1, 2011

Second Law of Thermodynamics: Heat flows from hot to cold. Heat is the movement of thermal energy from one object to another. Heat can only flow from an object of a higher temperature to an object of a lower temperature. Heat can be transferred from one object to another through conduction, convection and radiation.

Temperature is basically a speedometer for molecules. The faster they are wiggling and jiggling, the higher the temperature and the higher the thermal energy that object has. Your skin, mouth and tongue are antennas which can sense thermal energy. When an object absorbs heat it does not necessarily change temperature.

Materials: hot cup of cocoa

[am4show have=’p8;p9;p10;p37;p88;’ guest_error=’Guest error message’ user_error=’User error message’ ]

Leave a cup of hot coffee out on a cold morning. Does the coffee get warmer or cooler over time? Your coffee gets cooler, as heat travels from the coffee to the cool morning.

Learn more about this scientific principle in Unit 13.

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Ideal Gas Law

Sunday May 1, 2011

Pure substances all behave about the same when they are gases. The Ideal Gas Law relates temperature, pressure, and volume of these gases in one simple statement: PV = nRT where P = pressure, V = volume, T = temperature, n = number of moles, and R is a constant.

When temperature increases, pressure and volume increase. Temperature is basically a speedometer for molecules. The faster they are wiggling and jiggling, the higher the temperature and the higher the thermal energy that object has. Pressure is how many pushes a surface feels from the motion of the molecules.

Materials: balloon, freezer, tape measure (optional)

[am4show have=’p8;p9;p10;p37;p91;’ guest_error=’Guest error message’ user_error=’User error message’ ]

Hold a balloon in your hands and try to stuff it into a cup. Why is this so hard? You’re decreasing the volume and therefore increasing the pressure inside the balloon. (Since a balloon is so stretchy, this is near impossible to do without laughing.) You are compressing the balloon and thus increasing both the pressure and temperature inside the balloon slightly.

Blow up a balloon and stick it in the freezer overnight.

What happened? The balloon will shrink a bit because there is less pressure pressing on the inside of the balloon surface, holding the shape of the balloon. When you decrease temperature, the pressure and volume decrease as well.

Learn more about this scientific principle in Unit 13.

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States of Matter

Sunday May 1, 2011

There are three primary states of matter: solid, liquid, and gas.

Solids are the lowest energy form of matter on Earth. Solids are generally tightly packed molecules that are held together in such a way that they can not change their position. The atoms in a solid can wiggle and jiggle (vibrate) but they can not move from one place to another. The typical characteristics that solids tend to have are that they keep their shape unless they are broken and they do not flow.

Liquids have loose, stringy bonds between molecules that hold molecules together but allow them some flexibility. Liquids will assume the shape of the container that holds it.

Gases have no bonds between the molecules. Gases can be squished (compressed), and pure gases all behave the same way. (We’re going to learn more about this with the Ideal Gas Law.)

Materials: can of soda or glass of water

[am4show have=’p8;p9;p10;p37;p91;’ guest_error=’Guest error message’ user_error=’User error message’ ]

Grab a can of soda. Can you identify the states? The tin can is the solid, the drink is the liquid, and the bubbles are the gas.

There are two more states of matter: You’ll find plasma in the sun, neon signs, fluorescent lights, and small bits in a flame. The fifth state of matter has only been shown to exist in a lab (which was first discovered in the 1990s) and it occurs only in a very short temperature range near absolute zero.

Learn more about this scientific principle in Unit 3 and Unit 8.

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Basic Chemistry Safety Information

Monday November 1, 2010

Chemical Data & Safe Handling Information Sheet

What do I really need to know first? First of all, the chemicals in this set should be stored out of reach of pets and children. Grab the chemicals right now and stuff them in a safe place where accidents can’t happen. Do this NOW!

If you haven’t already done so, make sure to watch the introductory video for the Intermediate Chemistry and Advanced Chemistry lessons. They contain important information about the chemicals and lab equipment you’ll be using. When you’re done storing your chemicals out of reach, watch this video:

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Making Litmus Solution and Paper

Sunday October 31, 2010

You can go your whole life without paying any attention to the chemistry behind acids and bases. But you use acids and bases all the time! They are all around you. We identify acids and bases by measuring their pH.

Every liquid has a pH. If you pay particular attention to this lab, you will even be able to identify most acids and bases and understand why they do what they do. Acids range from very strong to very weak. The strongest acids will dissolve steel. The weakest acids are in your drink box. The strongest bases behave similarly. They can burn your skin or you can wash your hands with them.

Acid rain is one aspect of low pH that you can see every day if you look for it. This is a strange name, isn’t it? We get rained on all the time. If people were dissolving, if the rain made their skin smoke and burn, you’d think it would make headlines, wouldn’t you? The truth is acid rain is too weak to harm us except in very rare and localized conditions. But it’s hard on limestone buildings.

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Acids are liquids with a pH less than seven. A pH of seven is considered neutral. Bases are liquids with a pH greater than seven.

The combustion of fossil fuels such as oil, gasoline, and coal, create acid rain. Rain, normally at a pH of about 5.6, is always at least slightly acidic. Carbon dioxide is released into the air reacts with moisture in the air to form carbonic acid (HCO₃). Sulfur dioxide and nitrogen oxides are released into the air by fossil fuel combustion. They react with the slightly acidic rain and form sulfuric acid (H₂SO₄) and nitric acid (HNO₃).

We’re going to have fun with color changes in this experiment. We will make magic paper that changes color to tell us important things about liquids. It’s called litmus paper.

Litmus is harvested from a plant called a lichen, and bottled up as a powder. We’ll take the powder and make an acid-base indicator with it. Then we will use what we make to test solutions. And if you exercise your mind a bit, you will discover ways to use your litmus paper to discover things about the house and the world around you.

Materials:

Test tube rack
2 Test tubes
Test tube stopper
Distilled water
Ruler
Litmus powder (MSDS)
Measuring spoon
Denatured alcohol (MSDS)
Pipette
Sodium carbonate (Na₂CO₃) (MSDS)
Sodium hydrogen sulfate (NaHSO₄) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
Scissors
Filter paper (or paper towel or coffee filter)
Impervious surface

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet. Handle this chemical only with gloves, and be sure to read over the MSDS before using.

We will be using a ruler to measure the amount of water in a test tube. Ordinarily, chemists use more accurate measurement tools than a ruler. For the first part of this lab, making litmus solution, all we need is an approximate volume of water.

We will also be shaking a liquid in a test tube. Ever leave the top of a blender off when the “on” button is depressed? If not, just believe that it’s not a good idea. There is a certain technique t use when shaking up a liquid. We’ll place a stopper on a test tube and shake vigorously. Remember to do that as a chemist would do.

In a laboratory, whenever a chemist stoppers a solution and shakes it, it will be done the same way no matter if it is a toxic substance or just salt and water. That way, they are in the habit of doing it one way, the right way, so a mistake is not made at any time. A mistake at the wrong time could even be fatal.

Stopper the test tube firmly. Seat it well, but don’t grind down on the stopper. A test tube is thin-walled glassware, and as we grip harder it could collapse in our hand and now we have open cuts, blood, and toxic chemical is now entering your bloodstream. Stoppered firmly, we hold the test tube in our hand and place our thumb over the stopper for added security. To top off our safety measures, point the test tube, with a thumb firmly on top, away from us or anyone else and shake to our heart’s content.

We need to be careful with our chemicals. After using a chemical, cap the container to prevent spillage and contamination. Clean everything thoroughly after you are finished with the lab, or if you are going to reuse a tool. To dip a measuring spoon into one chemical after another, contaminates the chemicals and will affect your results.

C1000: Experiments 1-10
C3000: Experiments 5-18

Download Student Worksheet & Exercises

Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Place all chemicals, cleaned tools, and glassware in their respective storage places.

Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

You can test how acidic different substances are with an acid-base indicator like litmus paper.

Using the litmus powder in the chemistry set, we will make litmus paper. Our litmus paper is going to start out blue, and will turn red when an acid is placed on it. You can turn it back to blue by placing a few drops of a basic solution on it.

Let’s look a little further into the chemistry behind acids and bases. An acid produces hydronium ions (example: H₃O⁺) when dissolved in water. The ⁺ or ^– notation on a molecule tells us that after a chemical reaction creates it, the molecule is left with a net positive (electrons have been lost) or net negative charge (electrons have been added). Now, the ion could have more than just a +1 or -1 charge. Often, we will discover molecules with positive or negative charges of 2, 3, or 4.

Every liquid has a pH, and some of them may surprise you. Fruits contain citric acid, malic acid, and ascorbic acids, and the distilled white vinegar in your kitchen is a weak form of acetic acid. You’ll find carbonic acids in sodas, and lactic acid in buttermilk. And remember that acids taste sour and bases taste bitter? Don’t taste your chemicals, but the sour taste of vinegar and lemons and the bitter taste of club soda water and baking soda are familiar to people.

Generally, acids are sour in taste, change litmus paper from blue to red, react with metals to produce a metal salt and hydrogen, react with bases to produce a salt and water, and conduct electricity. Strong acids often produce a stinging feeling on mucus membranes (don’t ever taste an acid, or any chemical for that matter!).

Acids are proton donors (they produce H⁺ ions). Strong acids and bases all have one thing in common: they break apart (completely dissociate) into ions when placed in water. This means that once you dunk the acid molecule in water, it splits apart and does not exist as a whole molecule in water. Strong acids form H⁺ and an anion, such as sulfuric acid:

H₂SO₄ –> H⁺+ HSO₄

There are six strong acids:

hydrochloric acid (HCl)
nitric acid (HNO₃) used in fireworks and explosives
sulfuric acid (H₂SO₄) which is the acid in your car battery
hydrobromic acid (HBr)
hydroiodic acid (HI)
perchloric acid (HClO₄)

The record-holder for the world’s strongest acid are the carborane superacids (over a million times stronger than concentrated sulfuric acid). Carborane acids are not highly corrosive even though are super-strong. Here’s the difference between acid strength and corrosiveness: the carborane acid is quick to donate protons, making it a super-strong acid. However, it not as reactive (negatively charged) as hydrofluoric (HF) acid, which is so corrosive that it will dissolve glass, many metals, and most plastics.

What makes the HF so corrosive is the highly reactive Fl^– ion. Even though HF is super-corrosive, it’s not a strong acid because it does not completely dissociate (break apart into H⁺ and Fl^–) in water. Do you see the difference? Weak acids only partly dissociate in water, such as acetic acid (CH₃COOH).

On the other hand, bases taste bitter (again, don’t even think about putting these in your mouth!), feel slippery (don’t touch bases with your bare hands!), don’t change the color of litmus paper, but can turn red litmus back to blue, conduct electricity when in a solution, and react with acids to form salts and water. Soaps and detergents are usually bases, along with house cleaning products like ammonia.

Bases are also electron pair donors (they produce OH^– ions). Strong bases also completely dissociate into the OH^– (hydroxide ion) and a cation. LiOH (lithium hydroxide), NaOH (sodium hydroxide), KOH (potassium hydroxide), RbOH (rubidium hydroxide), CsOH (cesium hydroxide), Ca(OH)₂ (calcium hydroxide), Sr(OH)₂ (strontium hydroxide), and Ba(OH)₂ (barium hydroxide). Weak bases only partly dissociate in water, such as ammonia (NH₃)

pH stands for “power of hydrogen” and is a measure of how acidic a substance is. We can make homemade indicators to test how acidic (or basic) something is by squeezing out a special kind of juice (dye) called anthocyanin. Certain flowers have anthocyanin in their petals, which can change color depending on how acidic the soil is (hibiscus, hydrangeas, and marigolds for example). The more acidic a substance, the more red the indicator will become.

Going Further

Experiment: What household items are acidic or basic? Test various liquids to see. You may be surprised. Liquids you should be sure to test are vinegar, lemon or orange juice, baking soda, and cola. Use a dropper to place drops onto the paper instead of dunking the strip into your entire carton of orange juice. Litmus flavored orange juice is not my first choice in the morning.

Experiment: Collect soil samples from various places. Not the types of plants growing in the immediate area you are sampling from. Place about an inch of dirt in the bottom of a test tube. Fill the test tube near the top with water. Use distilled water if you have it for more accuracy. Stopper the tube and shake vigorously. Use your pipette to place drops of the water on your litmus paper and see if the soil is acidic or basic. Is there a correlation between the acidity of the soil and the plants that grow there?

Note: Litmus paper will not be able to indicate how acidic the rain in your area is, because the acid content in the water droplet is not high enough to register on the indicator. The effects of acid rain take time to develop and require more sensitive equipment to detect. [/am4show]

Energy from Sugar

Sunday October 31, 2010

This experiment is for advanced students.

Purple and white colors, making the whitewash that Tom Sawyer used, and produce an exothermic chemical reaction…..does it get any better?

Limewater is one of the compounds we work with in this experiment. Limewater was used in the old days of America. We’re talking about the 80’s…..the 1880’s.

Traveling medicine shows sold what was called “patent medicines”. These usually had no medicinal properties at all. The man in charge, the salesman of the operation, was called a “huckster”. He would have the one of the people gathered around to listen to him blow into limewater. Their exhaled breath contains carbon dioxide, and the lime water turned cloudy, just like in our experiment.

The man would hold up the glass with the cloudy limewater in it and pour in some of his fantastic remedy. As long as the “medicine” was acidic, it would turn the cloudy limewater clear. This was proof that the remedy would cure whatever ailed the person.

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Today, lime water is used in the traditional making of corn tortillas, tamales, and corn chips. People who have marine (saltwater) aquariums use lime water to assist in maintaining a healthy tank. Lime water is also used in the hide tanning process to remove hair. Parchment paper is made possible by the use of lime water as well. Here’s what you’ll need for your experiment with limewater:

Materials:

Granulated white sugar (MSDS)
Distilled water
Test tube rack
2 test tubes
On-hole rubber stopper
Measuring spoon
90⁰ bend glass tubing
Test tube clamp
Potassium permanganate (KMnO₄) (MSDS)
Sodium hydrogen sulfate (NaHSO₄ ) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
Measuring syringe
Calcium hydroxide, Ca(OH)₂ (MSDS) to add to H₂0 to make limewater (MSDS)

Keep the potassium permanganate solution from entering the glass tube and being transported into the limewater.

Saturated calcium hydroxide solution has been historically called lime water Ca(OH)₂ . That is what we will be bubbling our carbon dioxide into. It looks like water, but isn’t. Limewater smells like dirt and has an alkaline taste. (Don’t taste to find out. Not a safe laboratory practice.)

Saturated calcium hydroxide solution has been used as paint since the early years of the settlement of America. Ever hear of Tom Sawyer and the whitewashed fence? Whitewash is another name for limewater. We’re going to be using some pretty nasty chemicals, but you already follow all the safety precautions. Just remember to remember, and be careful.

The solution in one of your test tubes is going t undergo a chemical reaction to produce carbon dioxide. Another solution will be the indicator that CO₂ has been produced.

C3000: Experiment 64

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

When carbon dioxide is produced and bubbled into the lime water, a chemical reaction takes place.

Ca(OH)₂ + CO₂ –> CaCO₃ + H₂O

Calcium hydroxide (lime water) and carbon dioxide yields calcium carbonate and water. A milky precipitate forms that is calcium carbonate (CaCO₃).

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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Getting Air from Water

Sunday October 31, 2010

This experiment is for advanced students. This is a repeat of the experiment: Can Fish Drown? but now we’re going to do this experiment again with your new chemistry glassware.

The aquarium looked normal in every way, except for the fish. They were breathing very fast and sinking head first to the bottom of the tank. They would sink a few inches, then jerk into proper movement again.

The student had to figure out what was wrong. He had set up the aquarium as an ongoing science project, and it was his responsibility to maintain the fish tank. His grade depended on it.

He went to his mom for help. She looked over the setup. “Have you tested the water?”

A quizzical look on his face, the boy said, “Everything is normal nitrates, nitrites, hardness, alkalinity, and pH. The pH was a little acidic, but not outside the proper range.”

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His mother said to him, “Show me how you would look if you were gasping for air and look in the mirror while you do it.”

He did, and he remarked, “I look like my fish.” I swear a light bulb actually appeared over his head and lit all up. He said, “They need air!” His mom was standing near the aquarium holding an air pump, vinyl tubing, and an air stone.

“Looking for this?” His mom said. He and his mom set up the air pump and soon his fish were jumping in the air and kissing him on the cheek. Well, maybe not that last part, but you get the idea. Water does not contain an inexhaustible amount of oxygen in it. It must be replenished if there is something in the water that is using it up.

The oxygen carrying capacity of water varies with conditions. Rainbow trout are found in cold water streams because the colder the water, the more oxygen it will hold. Rainbow trout need lots of oxygen in their water to survive. Other species of fish are found only in warmer water because they are adapted to a condition of less oxygen in the water. Still other fish can gulp the air from the surface if the water is severely depleted of oxygen. I have seen carp gulping air as they swim around in a pond looking for food on a hot summer day.

In this experiment we will discover that water does contain oxygen. We will subject the water to heat and we will see the oxygen for ourselves.

Materials:

Test tube rack
Test tube
Test tube holder
Rubber stopper
90 degree bent glass tubing
Alcohol burner
Striker

Be careful not to let your water boil. Pressure will build up inside the test tube because only a small amount of pressure at a time can leave via the glass tubing. Pressure will build up and the stopper will fly off or the test tube will rupture. (Glass shrapnel and boiling water will get all over you. Not a pleasant thought.)

Inserting the glass tubing into and through the stopper is the most dangerous part of this lab or any other lab requiring this to be done. Most lab injuries, student or chemist, are due to cuts from broken glass. Proper technique will save you the pain of a deep cut. Lubricate the rubber stopper with glycerol if you have it. (It is a non-reactive laboratory grease that will not contaminate as badly as household or automotive oils and greases.) DO NOT use any other grease or oil. You probably don’t have any glycerol, so your second choice is just plain old water.

So, water on the tubing, gently start the glass tubing into the stopper. Don’t grip the glass with your hands, get a thick wash cloth, small towel, or work gloves and grab the tubing. Gently twist the tubing as you push gently on the tubing. Don’t pull to one side or the other, make your push a straight line. Once the tubing gets going, don’t stop unless you have to. Your second shot may be much more difficult because you have pushed a lot of the water off the tubing.

You are not going to see a chemical change. You are not going to work with chemicals. You are going to see for yourself that there is oxygen in water. That is, of course, what fish use up in the water. Unless it is replenished, fish can’t breath and they suffocate….not drown. The oxygen is replenished in the wild through various means. We can replenish the water with air pumps and water changes.

C3000: Experiment 51

Heated surfaces will be hot for awhile. Let things rest for a couple of minutes before doing your cleanup.

Your test tube probably has a blackened surface. It should wipe off easily, or will with a little soap, water, and a light touch.

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

The filter pump in your fish tank ‘aerates’ the water. The simple act of letting water dribble like a waterfall is usually enough to mix air back in. Which is why flowing rivers and streams are popular with fish – all that fresh air getting mixed in must feel good! The constant movement of the river replaces any air lost and the fish stay happy (and breathing). Does it make sense that fish can’t live in stagnant or boiled water?

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Working with Cataylsts

Sunday October 31, 2010

This experiment is for advanced students.

Don’t put this in your car….yet. Hydrogen generation, capture, and combustion are big deals right now. The next phase of transportation, and a move away from fossil fuels in not found in electric cars. Electric cars are waiting until hydrogen fuel cell vehicles become practical. It can be done and is being done.

Cars being powered by hydrogen are here, but not on the market yet. Engineers and chemists are always finding new ways to improve the chemical reaction that produces hydrogen and making the vehicles more efficiently use the fuel. Hydrogen fuel is not just easy to make, it is inexpensive, and the “exhaust” is water.

We will generate hydrogen in this lab. We will also see how combustible it is. Just let your imagination wander….just a bit and you will see noiseless cars and trucks zipping along the streets and interstates, carrying people and cargo. The Indianapolis 500 wouldn’t be quite the same, though. “And there they go, roaring, I mean quietly entering turn two…”

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Materials:

Goggles
Gloves
Measuring syringe
Water
Test tube rack
One-hole rubber stopper
Alcohol burner
Lighter
Test tube
Test tube holder
Water bath
Chemistry stand
Rubber tubing
90 degree bend glass tubing
Zn powder (MSDS)
Copper sulfate CuSo₄(MSDS)
Sodium hydrogen sulfate NaHSO₄(MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.

We will combine sodium hydrogen sulfate, water, and zinc. As soon as they are all together in our test tube, bubbles will begin forming in the solution. The bubbles will continue coming off, but we can speed up the reaction by adding a little copper sulfate. Now, instead of leisurely coming off, the gas is being given off quickly and we must act quickly ourselves to capture as much of the gas as possible. We can aid the gas movement ourselves by swirling the solution gently.

C3000: Experiment 74

Here’s what’s going on in this experiment:

NaHSO₄ + H₂O + Zn + CuSO₄–> H₂ + NaSO₄ + CuHSO₄ + ZnO

Sodium hydrogen sulfate is added to water and dissolved completely. Zinc is added and hydrogen gas is generated by the chemical reaction. Copper sulfate is added as a catalyst to speed up the generation of hydrogen.

Double replacement occurs where the compounds are broken apart and the pieces realign and re-bond with different parts of the original molecules, and zinc oxide is left as a byproduct of the oxidation of the zinc powder. Hydrogen gas is freed in the reaction.

Cleanup: We are going to clean everything thoroughly after we finish the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids must be neutralized before they can be washed down the drain. Solids are thrown in the outside trash.

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Hydrogen Peroxide

Sunday October 31, 2010

This experiment is for advanced students.

In industry, hydrogen peroxide is used in paper making to bleach the pulp before they form it into paper. Biologists, when preparing bones for display, use peroxide to whiten the bones.

At home, 3% peroxide combined with ammonium hydroxide is used to give dark-haired people their desired blonde moment. Peroxide is also used on wounds to clean them and remove dead tissue. Peroxide slows the flow from small blood vessels and oozing in wounds as well.

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Peroxide is a chemical produced in a Bombardier Beetle, and it squirts its irritating load into the face or onto the lips of a predator. Zebra fish produce peroxide after their skin is damaged. This action acts as a signal to produce an abundance of white cells to fight any infection and assist in the healing.

Scientists believe that healing can occur in humans in the same way. Future experiments may prove them right. It is also believed that people who have asthma have elevated levels of peroxide in their lungs, levels much higher than people without asthma.

Hydrogen peroxide can also help an animal that has eaten poison. A small amount of it can be put down the animal’s throat to induce vomiting and clear the poison out of their body as much as possible. Did your dog get too close to a skunk? There is no real “cure” other than a lot of time outside to air out, but peroxide mixed with hand soap is pretty good at removing the stink. Then, how you remove that stink from yourself…..another problem.

Materials:

2 test tubes
Burner
Lighter
Chemistry stand
Test tube holder
Glass jar
Water pan
Water
Rubber tubing
90^o glass tubing
3% Hydrogen peroxide (H₂O₂) (MSDS)

Hydrogen peroxide comes in a dark bottle because sunlight will slowly decompose hydrogen peroxide in the same way that we are doing with the exception that our way is much quicker.

When finished heating hydrogen peroxide, if you leave everything together, water will climb the tubing and attempt to enter the hot test tube. Cold water and hot peroxide are not safely compatible. To avoid this, remove the stopper from the test tube and set it aside while the solution cools.

Wait until all the equipment is cool enough to touch before disassembling for cleaning and storage.

When heating the test tube, be careful. Don’t heat in one place for too long. Move the flame of the burner around periodically to heat the reaction area of the test tube uniformly.

Don’t boil the peroxide too vigorously. If boiling gets too wild, remove the burner form the test tube until it calms down, then move it back to heat again.

At all times, keep the flame and peroxide apart…well apart.

Hydrogen peroxide is going to get broken down, is going to decompose, into the base elements of hydrogen and oxygen.

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Hydrogen peroxide (H₂O₂) breaks down with heat. A decomposition reaction occurs where hydrogen peroxide breaks down into its component elements, H₂ and O₂

2H₂O₂ –> 2H₂O + O₂

2 molecules of hydrogen peroxide are heated, creating a chemical decomposition reaction, producing 2 molecules of water and 1 molecule of oxygen.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain

Going further: Elephant’s Toothpaste

A really fun experiment with hydrogen peroxide is making Elephant’s toothpaste. It requires an adult helper, and is fun for the kid and the adult.

Materials:

Empty 20 or 24 ounce plastic bottle
3 % hydrogen peroxide
Liquid dish soap
Warm water
Food coloring
One packet or 2 1/2 ounces of yeast
One really big container to contain the big mess – laundry tub, bathtub, etc.

This video below is a demonstration of the Elephant Toothpaste experiment using much nastier chemicals than the ones I’ve mentioned above… the hot gas generated is actually oxygen. Enjoy!

Procedure:

Dissolve the yeast in a little warm water and stir well. Use just enough water to make a pourable liquid. Let it sit for about 5 minutes while you prepare the rest of the experiment.
Pour 1/2 cup of hydrogen peroxide, 1/4 cup of dish soap and a little bit of food coloring in the bottle. Swirl to mix and put the bottle in the middle of your large pot, container or sink.
Pour the yeast solution into the bottle. A funnel can help, but be prepared to pour fairly quickly and remove it again because the reaction will start as soon as you start pouring.
Stand back and watch the fun!

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Generating Oxygen

Sunday October 31, 2010

This experiment is for advanced students.

This time we’re going to use a lot of equipment… really break out all the chemistry stuff. We’ll need all this stuff to generate oxygen with potassium permanganate (KMNO₄). We will work with this toxic chemical and we will be careful…won’t we?

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Oxygen is pretty important… it’s only the single most important thing that mammals need. Besides breathing, oxygen is important for so much on this world. Oxygen is used in welding, rocket fuel, and water treatment. Without oxygen, there is no oxidation and no fire. Simply put, we wouldn’t have rusty bicycles or campfires. Can your believe it?

Potassium permanganate is an important chemical in the film industry. It is used to make props like cloth, ropes, and glass, appear “old”. Some films it has been used in are “Troy”, “Indiana Jones”, and “300”. The KMnO₄ stains any organic material. KMnO₄is also used as an antiseptic, and is used to treat skin ulcers and rashes. It is also used to treat foot fungus…..phew! People living in the country are sometimes plagued with an iron taste or a rotten egg smell in the water from their wells. Potassium permanganate can be used to remove the taste and smell from the water.

Materials:

Chemistry stand
Plastic tub
Water
2 test tubes
Test tube clamp
Potassium permanganate (KMnO₄) (MSDS)
Alcohol burner
Lighter
One-hole rubber stopper
Solid rubber stopper
90⁰ bend glass tube
Measuring spoon
Rubber tubing
Match
Wooden splint

Be careful inserting the glass tubing into the stopper. Wet the short end of the glass tube with water and gently push and twist the glass through the stopper. Wear work gloves and work carefully and slowly. Do not use oil or grease you have laying around the house.

When lighting the oxygen in the test tube, use a wooden splint. Wooden splints can be purchased from craft stores, or make your own by shaving thin strips from a piece of pine wood.

C3000: Experiment 58

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

2KMnO₄ + O₂ –> K₂MnO₄ + MnO₂ + O₂

Potassium permanganate is heated and produces potassium manganate, manganese dioxide, and oxygen

Oxygen is generated by heating the KMnO₄, and is collected in the test tubes. We will test the contents of the tubes to see if oxygen has been generated. What do you think will happen when a glowing splint is pushed up inside the test tube? Don’t know? Do the experiment and try to figure it out. Remember, in order for there to be flame, you need fuel and oxygen. If that gas was carbon dioxide, what would happen when the glowing splint was placed inside?

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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Detonating Bubbles

Sunday October 31, 2010

This experiment is for advanced students.

Zinc (Zn), is a metal and it is found as element #30 on the periodic table. We need a little zinc to keep our bodies balanced, but too much is very dangerous.

Zinc is just like the common, everyday substance that we all know as di-hydrogen monoxide (which is the chemical name for water). We need water to survive, but too much will kill us.

DHMO: In chemistry, “Di” equals the number 2; hydrogen is H; mono equals the number one; and oxide is derived from oxygen, and its symbol is O. Put these together and you have Di-hydrogen (H₂), and mono oxygen (O). Put them together, what do you have? Water!

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Materials:

Goggles
Gloves
Test tube rack
3 test tubes
Burner
Lighter
Zinc powder (Zn) (MSDS)
Calcium hydroxide (Ca(OH)2 (MSDS)
Rubber tubing
Measuring spoon
Solid rubber stopper
Pan
Water
Chemistry stand
Test tube holder
90^o glass tubing
One-hole rubber stopper
Evaporating dish
Dish soap
Wood splint
Measuring syringe

Be careful of the hot test tubes! It may not look hot, but don’t find out the hard way. If a chemist wants to know if something is hot, he places the back of his hand near the surface. If he feels heat, he concludes that it is hot. That’s the same way we test a person’s forehead for a fever. The back of your hand is more sensitive than the front.

Zinc, zinc oxide, and calcium hydroxide are dangerous chemicals. Use your safety equipment. Dispose of the residue in the test tube in the outside garbage.

We will be creating hydrogen gas by making a heterogeneous mixture of zinc powder and calcium hydroxide and heat it. The hydrogen bubbles into test tube in a water bath. When we mix our test tube of hydrogen with the air the room, the hydrogen burns…it actually explodes. Our amounts are small, but you will witness a cool, small, explosion.

In the second part of the lab we will again create hydrogen. This time, we have a tricky way to add oxygen to the hydrogen and we are able to create a ration of 2 parts hydrogen to 1 part oxygen. This is the perfect ratio to make the most explosive mixture of hydrogen and oxygen. The explosion here is very cool.

C3000: Experiment 76-78

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

In the first part of the lab we produce hydrogen by combining two dry chemicals and heating them. Now two things will happen. Calcium hydroxide, when heated, produces water.

Ca(OH)₂ –> CaO + H₂O

Calcium hydroxide, when heated, produces calcium oxide and water. This is an oxidation reaction because the calcium oxidizes….combines with the oxygen and releases the other elements.

Next, Zinc will react with water created by calcium hydroxide. As the Ca(OH)₂ is heated and turns to water and calcium oxide, the zinc then reacts and produces zinc oxide and hydrogen gas.

Zn + H₂O –> ZnO + H₂

Zinc when heated in the presence of water, produces zinc oxide and hydrogen gas. This is a single replacement reaction as oxygen kicks out hydrogen and replaces it with zinc.

Here’s the safety information for the products of the reaction:

Zinc Oxide (MSDS)
Hydrogen (MSDS)
Calcium Oxide (MSDS)

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the outside garbage. Liquids can be washed down the drain.

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Desalination

Sunday October 31, 2010

This experiment is for advanced students.

Lewis and Clark did this same experiment when they reached the Oregon coast in 1805. Men from the expedition traveled fifteen miles south of the fort they had built at the mouth of the Columbia River to where Seaside, Oregon now thrives.

In 1805, however, it was just men from the fort and Indians. They built an oven of rocks. For six weeks, they processed 1,400 gallons of seawater, boiling the water off to gain 28 gallons of salt.

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Lewis and Clark National Historic Park commemorates the struggles of the expedition. (The reconstructed fort is also there to visit.) It is Fort Clatsop National Memorial, and is quite an experience to go through the fort.

Lewis and Clark went to great lengths to obtain salt. The men had been complaining that fish without salt had become something to avoid. Salt is important to us as well. It is a condiment, an addition to food that brings out the food’s natural flavor. Besides its food value, salt is used as a food preservative. It destroys bacteria in food by removing moisture from their “bodies” and killing them.

Sodium chloride, table salt, NaCl….they’re all acceptable names for salt. If NaCl is broken down into its component elements, the elements don’t act like our friend salt. Its components are sodium and chlorine.

Sodium is a highly reactive alkali metal, element #11 on the periodic table. It is exothermic in water, which means that is gives of heat as it reacts with water. Small pieces tossed into water will react with it. The sodium particles give off heat that melts them into round balls. The sodium particles bounce and scurry around the surface at a high rate of speed. If you ever get the chance to observe this, do it. The reaction continues until the sodium is gone. Sodium, as it reacts with the water, changes chemically into sodium hydroxide. These cool things that sodium does are also dangerous. Sodium and sodium hydroxide are caustic…they are so pH basic that they will burn you.

Chlorine is a halogen, group 17, element #17. Chlorine is used in bleach, disinfectants, and in swimming pool maintenance. It seems that anywhere you want to remove color or life, chlorine is your element. This property of chlorine to kill was used in war. (It would react with the mucous linings in their throat, undergoing a chemical reaction to turn into hydrochloric acid in their throats. Hydrochloric acid is a very dangerous acid, usually fatal once inside you.) Chlorine is known as bleach at home. Never, never, drink it or breathe its fumes.

Materials:

Goggles
Gloves
Jar or glass
2 90o glass tubes
Chemistry stand
Rubber tubing
Test tube clamp
Erlenmeyer flask
One-hole rubber stopper
Wire screen
Alcohol burner
Lighter
Test tube
Water
Saltwater
Heating rod

Look out for the hot flask and other glassware. Allow everything to cool before cleaning.

When done heating, move the rubber tubing out of the water. There is a difference in pressure between the heated glassware and the water bath. That difference in pressure will cause the water to enter the tubing and cool water will flow into the hot glassware and could cause catastrophic damage to the glassware.

Never…Never!….drink the results of an experiment. Yeah, I know that plain old water is supposed to be in the test tube, but follow the experiment’s safety guidelines. You’ve had other stuff in that test tube, too.

C3000: Experiment 83

Here’s what’s going on in this experiment:

That flask of saltwater will start to boil, and water vapor will leave the flask and travel to the test tube. There is no chemical change occurring in this experiment, but a physical one. A physical change involves a change in state (melting, freezing, vaporization, condensation, sublimation). Physical changes are things like crushing a can, melting an ice cube, breaking a bottle, or boiling saltwater until there is nothing left but salt and steam.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain

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Cold Light

Sunday October 31, 2010

This experiment is for advanced students.

Glo-sticks! Parents hang them from their trick or treaters, backpackers read with them light late at night in a tent. Glo-sticks work on the principle of chemiluminescence. Chemiluminescence is defined as emitting light without heat as the result of a chemical reaction.

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We might be tempted to mistake cold light for fluorescence. Fluorescent light is created by exciting electrons, not from a chemical reaction.

Luminol is one of out chemicals in this lab. Luminol is most famous by its use by criminal investigators when they need to locate blood. What makes this happen is that the iron in the blood reacts with the luminol to generate cold light.

Let’s have fun creating our own little version of cold light….I’ll use the term “cold light” from now on. It takes a long time to type out “chemiluminescence”.

Materials:

Glass jar
Measuring cup
Water
Test tube
Luminol C₈H₇N₃O₂ (MSDS)
Sodium hydroxide NaOH (MSDS)
Stir rod
Hydrogen peroxide H₂O₂ (MSDS)
Potassium hexacynoferrate II K₃Fe(CN)₆ (MSDS)
Measuring spoon

The chemical reaction in this lab produces light without heat. Photons of light are emitted, but no heat. That must be cold heat. The light emitted from this lab is not as bright as a glow stick, but it still emits light. The same principle is used in the glow sticks. Our light will be seen as a low power blue-green light. The cold light effect is best viewed in a darkened room.

C3000: Experiments: 105, 110

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Solution #1 C₈H₇N₃O₂+ NaOH is added to Solution #2 H₂O₂+ K₃Fe(CN)₆ –> Cold Light

Cold Light is the production of light from a chemical reaction without the radiation of heat. There are three types of cold light reactions: Fluorescence, phosphorescence, and chemiluminescence. In chemiluminescence no radiation is absorbed. A chemical reaction provides the energy needed to emit light. Chemiluminescence is usually referred to as “cold light”. It rolls off the tongue much better and is easier to type. (I find that every time I type “chemiluminescence” I spell it differently.)

People used to rub their walking sticks with a luminescent jellyfish to light the path while walking. Today, light sticks from the store aren’t made from jellyfish. Modern-day light sticks involve a different reaction from the experiment you will be performing. We will have the luminal glow, but light sticks use a different reaction.

Light sticks use a di-ester of hydrogen peroxide that oxidizes in an organic solvent. The reaction is tons slower, giving a light stick a life span of hours instead of seconds or minutes. Dyes are added to produce different colors. When you break the class vial inside to activate the light stick, you mix the luminol with the other reactant, and the chemical reaction is under way.

A general chemical equation producing cold light:

A + B –> high energy intermediate à products + light

The luminol is oxidized by B. This oxidation produces cold light.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain. Solids are thrown in the trash.

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Carbon Dioxide

Sunday October 31, 2010

This experiment is for advanced students. This lab builds on concepts from the previous carbon dioxide lab.

Limewater….carbon dioxide…indicators. We don’t know too much about these things. Sure, we know a little. Carbon dioxide is exhaled by us and plants need it to grow. Burning fossil fuels produces carbon dioxide.

Indicators…something we observe that confirms to us that something specific is happening. Lime water turns cloudy and forms a precipitate in the presence of carbon dioxide. Blue litmus paper turns red in the presence of an acid. The dog barking at the door and dancing around indicates that you better let the dog out, and quick, to avoid….a pet spill?

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Materials:

Limewater from a previous lab (MSDS)
One-hole rubber stopper
90⁰ bend glass tubing
Test tube rack
2 Test tubes
Sodium hydrogen sulfate (NaHSO₄) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
Sodium carbonate (Na₂CO₃) (MSDS)

When pouring our limewater into the test tube, be careful! Limewater is dangerous to your skin and your nasal passages. Pour just the limewater into the test tube, not any solids that may have gotten into the limewater container.

A chemical reaction will occur between sodium hydrogen sulfate, sodium carbonate, and water. We could have used any combination of chemicals for this lab that will produce carbon dioxide (CO₂), but these chemicals are already in our kits, so……

The reaction will create a gas, that gas, we think, is carbon dioxide. If we are right, we will be bubbling CO₂ gas into lime water. If we observe the limewater becoming cloudy and if a precipitate forms on the bottom of the test tube, that is a positive indicator that CO₂is present.

C3000: Experiment 31

Here’s what’s going on in this experiment:

Some combination of chemicals will produce carbon dioxide –> CO₂ + ?

Notice that specific chemicals are not in the chemical equation? The actual chemistry of the chemical reaction is not our focus in this lab. We want to experience how an indicator can test for a particular compound or element.

Instead of sodium hydroxide and sodium carbonate and water, we could choose to combine vinegar and baking soda for example. Even simple household supplies can be chemicals for our experiments.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain. Solids are thrown in the trash.

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Zinc Dust

Sunday October 31, 2010

This experiment is for advanced students.

Who gets to burn something today? YOU get to burn something today!

You will be working with Zinc (Zn). Other labs in this kit allow us to burn metal, but there is a bit of a twist this time. We will be burning a powder.

Why a powder instead of a solid ribbon or foil as in the other labs? Have you heard of surface area being a factor in a chemical reaction? The more surface area there is to burn, the more dramatic the chemical change. So, with this fact in mind, a powder should burn faster or be more likely to burn than a large solid.

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Zinc (Zn) is a metallic element. It is element #30 on the periodic table. Chemically, it is similar to magnesium, another element that we use in our experiments.

Brass is an alloy of zinc and copper. Brass has been an important metal since the 10^th century B.C. Alchemists in the dark ages burned zinc in air, just like we will do, to make what they called “white snow”. Their “white snow is our zinc oxide.

Zinc is an important element in our lives. Zinc deficiency causes lack of proper growth, delayed physical maturation, and susceptibility to infection. Zinc deficiency contributes to the death of 800,000 children per year. Excess zinc in our bodies can cause problems for us as well.

Materials:

Alcohol burner
Lighter
Measuring spoon
Zinc powder (MSDS)
Porcelain tile work surface

Remember to dispose of your zinc oxide in the outside trash, and conduct your experiment in a well ventilated area. Fumes from this experiment are irritating and a little dangerous.

C3000: Experiment 53

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Zinc powder will burn in the presence of oxygen, producing interesting colors. The flame from burning zinc is blue, as the zinc undergoes a chemical change to become zinc oxide. Zinc oxide is thermochromic. That means that it changes colors depending on the temperature. When cool, ZnO is white. When heated, zinc oxide turns yellow, and as it cools, returns to become a white powder again. The color changes are caused by a small loss of oxygen at high temperatures, and a small gain of oxygen as it cools in air.

2Zn + O₂ –> 2ZnO

Zinc powder burned in air reacts with the oxygen and turns into zinc oxide. Zinc oxide is used in sunscreen and to treat burns, cuts, and diaper rash.

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place all chemicals and cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage.

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Magnesium Battery

Sunday October 31, 2010

Magnesium is one of the most common elements in the Earth’s crust. This alkaline earth metal is silvery white, and soft. As you perform this lab, think about why magnesium is used in emergency flares and fireworks. Farmers use it in fertilizers, pharmacists use it in laxatives and antacids, and engineers mix it with aluminum to create the BMW N52 6-cylinder magnesium engine block. Photographers used to use magnesium powder in the camera’s flash before xenon bulbs were available.

Most folks, however, equate magnesium with a burning white flame. Magnesium fires burn too hot to be extinguished using water, so most firefighters use sand or graphite.

We’re going to learn how to (safely) ignite a piece of magnesium in the first experiment, and next how to get energy from it by using it in a battery in the second experiment. Are you ready?

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Materials:

magnesium strip (MSDS)
matches with adult help
tile or concrete surface (something non-flammable)
gloves, goggles

Burning magnesium produces ultraviolet light. This isn’t good for your eyes, and the brightness of the flame is another danger for your eyes. Avoid looking directly into the flame.

Burning magnesium is so hot that if it gets on your skin it will burn to it and not come off. As difficult as burning magnesium is to put out, avoid letting the burning metal come in contact with you or anything else that might catch fire.

As explained later in this lab, magnesium burns in carbon dioxide. Therefore, a CO2 fire extinguisher won’t work to put it out. Water won’t work, CO2 won’t work. It takes a dry chemical fire extinguisher to put it out, or just wait for it to burn up completely on its own.

Magnesium is a metal, and in this experiment, you’ll find that some metals can burn. The magnesium in this first experiment combines with the oxygen in the air to produce a highly exothermic reaction (gives off heat and light). The ash left from this experiment is magnesium oxide:

2Mg _(s) + O₂ _(g) –> 2Mg O _(s)

Not all the magnesium from this experiment turned directly into the ash on the table – some of it transformed into the smoke that escaped into the air.

Caution: Do NOT look directly at the white flame (which also contains UV), and do NOT inhale the smoke from this experiment!

C3000: Experiment 52

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

As you burn your magnesium, you will get your very own fireworks show….a little one, but still cool.

2Mg + O₂ –> 2MgO

Magnesium burned in oxygen yields magnesium oxide. Because the temperature of burning magnesium is so high, small amounts of magnesium react with nitrogen in the air and produce magnesium nitride.

3Mg + N₂ –> 2Mg₃N₂

Magnesium plus nitrogen yield magnesium nitride. Magnesium will also burn in a beaker of dry ice instead of in air (oxygen).

2Mg + CO₂ –> 2MgO + C

Magnesium burned in carbon dioxide yields magnesium oxide and carbon (ash, charcoal, etc.)

Cleanup: Rinse off and pat dry the rest of the magnesium strip.

Storage: Place everything back in its proper place in your chemistry set.

Disposal: Dispose of all solid waste in the garbage.

Magnesium Battery

Now let’s see how to make a battery using magnesium, table salt, copper wire, and sodium hydrogen sulfate (AKA sodium bisulfate).

Materials:

magnesium strip
test tube and rack
light bulb (from a flashlight)
2 pieces of wire
measuring cup of water
salt (sodium chloride)
copper wire (no insulation, solid core)
measuring spoon
sodium hydrogen sulfate (NaHSO4) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
gloves, goggles

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet. Handle this chemical only with gloves, and be sure to read over the MSDS before using.

C1000: Experiment 75
C3000: Experiment 295

We’re going to do another electrolysis experiment, but this time using magnesium instead of zinc. In the previous electrolysis experiment, we used electrical energy to start a chemical reaction, but this time we’re going to use chemical energy to generate electricity. Using two electrodes, magnesium and copper, we can create a voltaic cell.

TIP: Use sandpaper to scuff up the surfaces of the copper and magnesium so they are fresh and oxide-free for this experiment. And do this experiment in a DARK room.

How cool is it to generate electricity from a few strips of metal and salt water? Pretty neat! This is the way carbon-core batteries work (the super-cheap brands labeled ‘Heavy Duty’ are carbon-zinc or ‘dry cell’ batteries). However, in dry cell batteries scientists use a crumbly paste instead of a watery solution (hence the name) by mixing in additives.

In this chemical reaction, when the magnesium metal enters into the solution, it leaves 2 electrons behind and turns into a magnesium ion:

Oxidation: Mg _(s) –> Mg²⁺_(aq) + 2e^–

The magnesium strip takes on a negative charge (cathode), and the copper strip takes on a positive charge (anode). The copper strip snatches up the electrons:

Reduction: Cu²⁺_(aq) + 2e^– –> Cu _(s)

and you have a flow of electrons that run through the wire from surplus (cathode) to shortage (anode), which lights up the bulb.

Note: You can substitute a zinc strip or aluminum strip for the magnesium strip and a carbon rod (from a pencil) for the copper wire.

Going further: You can expand on this experiment by substituting copper sulfate and a salt bridge to make a voltaic cell from two half-cells in Experiment 16.5 of the Illustrated Guide to Home Chemistry Experiments.

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Burning Sulfur

Sunday October 31, 2010

This experiment is for advanced students.

Brimstone is another name for sulfur, and if you’ve ever smelled it burn…..whoa….I’m telling you ….you will see for yourself in this lab. It is quite a smell, for sure. Sulfur is element #6 on the periodic table. Sulfur is used in fertilizer, black powder, matches, and insecticides. In pioneer times sulfur was put into patent medicines and used as a laxative.

To further the evil reputation of sulfur, or brimstone, when sulfur is burned in a coal fired power plant, sulfur dioxide is produced. The sulfur is spewed into the air, where it is reacts with moisture in the air to form sulfuric acid. The clouds get full and need to let go of this sulfuric acid. Down comes the acid rain to wreak havoc on the masonry and plant life below.

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Materials:

Goggles
Gloves
Measuring spoon
Sulfur (MSDS)
Alcohol burner
Lighter
Test tube of O₂

Be careful when bending the ends of your measuring spoon. Bend them where you need them and leave them alone. Continuing to bend, straighten, and re-bend will weaken the metal and cause your measuring spoon to break. We will do this experiment to compare the flames produced by burning sulfur in air and oxygen

C3000: Experiments: 36,60

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

S + O₂ –> SO₂

Sulfur and oxygen are heated and sulfur dioxide is produced. This is a synthesis reaction because the sulfur and the oxygen react and form a new substance, sulfur dioxide. We see the flame of sulfur dioxide burn in air. Small flame, little smoke. When the flame is left lit and placed in the oxygen, the flame flares up and lots of white smoke is generated. It appears that sulfur’s flame burns brighter and stronger in pure oxygen.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain. Solids are thrown in the trash.

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Making Copper

Sunday October 31, 2010

In this lab, we’re going to investigate the wonders of electrochemistry. Electrochemistry became a new branch of chemistry in 1832, founded by Michael Faraday. Michael Faraday is considered the “father of electrochemistry”. The knowledge gained from his work has filtered down to this lab. YOU will be like Michael Faraday. I imagined he would have been overjoyed to do this lab and see the results. You are soooo lucky to be able to take an active part in this experiment. Here’s what you’re going to do…

You will be “creating” metallic copper from a solution of copper sulfate and water, and depositing it on a negative electrode. Copper is one of our more interesting elements. Copper is a metal, and element 29 on your periodic table. It conducts heat and electricity very well.

Many things around you are made of copper. Copper wire is used in electrical wiring. It has been used for centuries in the form of pipes to distribute water and other fluids in homes and in industry. The Statue of Liberty is a wonderful example of how beautiful 180,000 pounds of copper can be. Yes, it is made of copper, and no, it doesn’t look like a penny…..on the surface. The green color is copper oxide, which forms on the surface of copper exposed to air and water. The oxide is formed on the surface and does not attack the bulk of the copper. You could say that copper oxide protects the copper.

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Our bodies use copper to our advantage, but in a proper form that is not toxic. Too much copper will make you sick and could kill you. Remember…don’t eat your chemistry set!

Materials:

Carbon rod (MSDS)
Copper sulfate (CuSo₄) (MSDS)
Aluminum foil
9V battery with clip
2 wires
Disposable cup
Water

You are going to make a saturated solution of copper sulfate (CuSO₄) in water. Pour a measuring spoon of granulated copper sulfate in the measuring cup of water. Stir well. Continue adding a spoonful and stirring until no more crystals will go into solution. The solution is saturated when no more crystals will dissolve and there are undissolved crystals at the bottom of the container.

C1000: Experiment 74

C3000: Experiment 121, 289

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

CuSO₄ + H₂O (Copper sulfate is added to water)

CuSO₄ + H₂O à Cu²⁺ + SO₄^2-(Copper sulfate plus water yields positively charged carbon ion and negatively charged sulfate ion)

When mixed with water, copper sulfate dissociates into copper and sulfate ions. Notice that the ions, now separated, take on negative and positive charges.

Next, 9V of electricity is passed through the solution with an electrode of carbon and an electrode of aluminum foil inserted into the solution. As electricity flows from one electrode to another, the copper ions, being positively charged, are attracted to the negative electrode. You can confirm this in two ways. One, if litmus paper, held close to an electrode, turns blue, that is the negative electrode. The other way is to just follow the negative lead from the battery to the negative electrode.

As the process moves along, the negative electrode gains copper ions. Evidence of this is seen on the surface of the electrode.

Here’s the breakdown of the entire process:

When the copper sulfate (CuSO4) mixed with water (H2O), the copper sulfate dissociated:

CuSO₄ –> Cu²⁺ + SO₄^2-

When power is added to the solution, the copper ions move toward the negative cathode (carbon rod) and take electrons from it, forming solid copper right on the electrode:

Cu²⁺+ 2e^– –> Cu_(s)

On the positive anode (the aluminum foil), you’ll see bubbles instead of a solid forming. The anode attracted electrons from the water molecule to form oxygen bubbles:

6H₂O –> O₂ + 4H₃O⁺ + 4e^–

Let’s put these two reactions together to get the overall reaction of:

2Cu²⁺ + 6H₂O –> 2Cu + O₂ + 4H₃O⁺

Note the difference between galvanic cells and electrolytic cells: galvanic use spontaneous chemical reactions (like in a car battery) to generate electricity, and electrolytic cells use electricity to make the chemical reaction to occur and move electrons to move in a way they would go on their own (like in this experiment).

Clean up: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. Rinse three times, wash with soap, rinse three times.

Wipe off the carbon rod to remove the copper. The aluminum goes in the trash, but the solution and solids at the bottom cannot. The liquid contains copper, a toxic heavy metal that needs proper disposal and safety precautions. Another chemical reaction needs to be performed to remove the heavy metal from the copper sulfate. Add a thumb sized piece of steel wool to the solution. The chemical reaction will pull out the copper out of the solution. The liquid can be washed down the drain. The solids cannot be washed down the drain, but they can be put in the trash. Use a little water to rinse the container free of the solids.

Place all chemicals, cleaned tools, and glassware in their respective storage places.

Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

Going Further

Here is a link to information about making your own geode (crystal lined rock) of copper sulfate crystals:

http://chemistry.about.com/od/growingcrystals/ht/geode.htm

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Making Chlorine

Sunday October 31, 2010

If we don’t have salt, we die. It’s that simple. The chemical formula for salt is NaCl. Broken down, we have Na (sodium) and Cl (chlorine). Either one of these can be fatal in sufficient quantities. When chemically combined, these two deadly elements become table salt. What once could kill now keeps us alive. Isn’t chemistry awesome?

Chlorine, element 17, is called a halogen as are all the elements in the 17^th row. All halogens have similar chemical properties. They are highly reactive nonmetals, and react easily with most metals. Sodium is a metal, and is bonded with sodium in the table salt used in this lab. Besides being found in salt, chlorine has many uses in our world such as killing bacteria in our water, making plastic, cleaning products, and the list goes on. A very useful chemical, and is among the top ten chemicals produced in the United States. Ever since its discovery in 1774, chlorine has been very useful. It is found in nature in sodium chloride, but in very small concentrations. Seawater, the most abundant source of chlorine, has a concentration of only 19g of chlorine per liter.

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Although chlorine is abundant in nature (about 2% of the mass of the ocean is chloride ions), scientists have developed a safe way to make chlorine. Chlorine has been manufactured for a hundred years through different processes: Membrane Cell, Diaphragm Cell, and Mercury Cell processes. In the first two processes, salt water (NaCl + H₂O) and caustic soda (NaOH) are used along with a power supply to generate chlorine and hydrogen gas.

Molecules that contain chlorine that find their way into the upper atmosphere can destroy the ozone layer. The ozone-oxygen cycle is a chemical process that transforms the harmful UV light (240-310nm) from the sun into heat. The oxygen and ozone molecules are constantly being switched back and forth as the sun’s UV breaks down the ozone and the oxygen molecules reacts with other oxygen atoms.

This reaction converts UV radiation into thermal energy which heats up the atmosphere (this reaction happens slowly):

O₃ –> O₂ + O

If two free oxygen atoms meet, they form a new oxygen molecule:

2O –> O₂

If this new molecule meets another free oxygen, it creates another ozone molecule:

O₂ + O –> O₃

If an ozone and an oxygen molecule meet, they form two oxygen, and this process removes ozone from the atmosphere. This process is very slow, however, so the naturally occurring reaction of:

O₃ + O –> 2O₂

is nothing to worry about. It’s when this reaction gets sped up by catalysts that we have to pay close attention. There are many catalysts that can speed up the removal of ozone, such as chlorine, bromine, and nitric oxide (NO₃). And since they are catalysts in the reaction (meaning they simply speed up the reaction without getting used), they can do this over and over again before they move out of the atmosphere completely. One chlorine atom can speed up (catalyze) tens of thousands of ozone removal reactions before it moves out of the stratosphere. Scary, huh?

CFCs (chlorofluorocarbons) such as aerosols, refrigerants (R-12), and solvents have been banned because of their damaging effect on the atmosphere. When sunlight hits a CFC, it splits off a chlorine ion:

CCl₃F –> CCl₂F^– + Cl^–

This free chlorine ion catalyzes the ozone into oxygen:

O₃ + O^– + Cl^– –> 2 O_{2 +}Cl^–

The chlorine we’re going to generate in our experiment is a minuscule amount. Even so, it is still a good idea to perform this experiment in an area with good ventilation or outdoors.

Remember to wear your gloves and goggles. True, the amount of chlorine produced is small and pretty harmless. But there are several factors that make it prudent to wear your protection. Not everyone has the same sensitivity to chemicals. Even in this lab, a person could get their skin irritated to some degree. Eyes are very sensitive organs, and I know I don’t want any amount of chlorine contacting my eyes.

Here’s what you’re going to need to do this experiment:

Materials:

9V battery clip
carbon rod
wires
disposable cup
salt
water
aluminum foil
gloves, goggles

We will be observing a decomposition reaction. A decomposition reaction separates a substance into two or more substances that may differ from each other and from the original substance.

ZcQr –> Zc + Qr

When separated, the free elements to the right of the equation become ions, one positively charged and one negatively charged.

A very important concept to learn in this lab is that charged particles (ions) will move toward either a positive or negative electrode. The ions that move toward the anode (positive terminal) are anions, and the ones that move toward the cathode (negative) are cations.

Decomposition of any kind is the breaking down of the whole into smaller parts that were once part of the whole.

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

An electrical charge is passing through a saturated solution of salt (NaCl). It will sit there and just be salt unless that electrical charge is imposed on it. The electrical charge excites the molecules, and causes the molecules of salt to decompose, to pull apart, to break into simpler parts. These ions are negatively and positively charged. Negatively charges particles have more electrons than protons and seek a balance. In order to have an electric current, you need to have positive and negative electrodes. Opposites attract, so the negative ions move to the positive electrode and the positive ions are attracted to the negative electrode.

NaCl –> Na⁺ + Cl^–

Sodium chloride decomposes into sodium and chlorine ions.

The anode (positive, carbon rod) soaks up free electrons, which get pumped to the cathode (negative, aluminum foil) and released into the solution. If you press litmus paper against the aluminum strip, you’ll find it’s blue (basic), and red when pressed to the anode (carbon rod). The bubbles on the carbon rod are made of chlorine. The chlorine ions in the solution are attracted to the positive pole (carbon rod) and quickly combine to form chlorine gas:

2Cl^– –> Cl₂

The sodium ions move toward the aluminum foil and split the water molecule into ions:

H₂O –> H⁺ + OH^–

The hydrogen ions are converted into hydrogen gas:

2H⁺ –> H₂

The sodium ions (Na+) that remain in the solution combine with the OH- ions to create sodium hydroxide which turns the litmus paper blue:

Na⁺ + OH^– –> NaOH

The main concept I want you to understand with this experiment is that charged particles (ions) will move toward either a positive or negative electrode. The ions that move toward the anode (positive terminal) are anions, and the ones that move toward the cathode (negative) are cations.

Before you dispose of the solution, try this variation on the experiment: remove the foil and hold a salt-water filled test tube (filled to the top with salt water and capped with a gloved thumb and submerged into the solution). Place the cathode wire into the tube and you’ll see bubbles rising up into the tube. What type of gas is it? (Hint: wait until the tube is nearly full before removing it and using a match to test.)

For C3000 Students: Use this experiment as the basis for Experiment 123.

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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Electrochemistry

Sunday October 31, 2010

Electricity. Chemistry. Nothing in common, have nothing to do with each other. Wrong! Electrochemistry has been a fact since 1774. Once electricity was applied to particular solutions, changes occurred that scientists of the time did not expect.

In this lab, we will discover some of the same things that Farraday found over 300 years ago. We will be there as things tear apart, particles rush about, and the power of attraction is very strong. We’re not talking about dancing, we’re talking about something much more important and interesting….we’re talking about ELECTROCHEMISTRY!

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Materials:

Test tube rack
9V battery clip
9V battery
Flashlight lamp
Gloves
Electrical wires
Aluminum foil
Water
Sugar
Salt
Sodium carbonate (MSDS)
Measuring spoon

When the salt sodium chloride (NaCl) mixes with water, it separates into its positively (Na+) and negatively (Cl-) charged particles (ions). When a substance mixes with water and separates into its positive and negative parts, it’s called a ‘salt’.

Salts can be any color of the rainbow, from the deep orange of potassium dichromate to the vivid purple of potassium permanganate to the inky black of manganese dioxide. Did you know that MSG (monosodium glutamate) is a salt? Most salts are not consumable, as in the lead poisoning you’d get if you ingested lead diacetate.

If you pass a current through the solution of salt and water, opposites attract: the positive ions are attracted tot he negative pole and the negative ions go toward the positive pole. These migrations ions allow electricity to flow, which is why ‘salt’ solutions conduct electricity.

C1000: Experiments 66-70

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Our experiment uses a saturated solution of table salt that is just sitting in a container minding its own business. That just won’t do! We must intervene. Our 9V battery pushes its voltage through the saltwater. That electric current tears the sodium from the chlorine. These positively and negatively charged ions rush about, looking for something they are attracted to. Opposites attract, so positively charged sodium ions find spending time with the negative electrode a treat. They are very happy together. Negatively charged chlorine ions are attracted to the positive electrode. The match is wonderful, and the negativity and the positivity somehow enjoy the time spent with each other.

NaCl –> Na⁺ + Cl^–

Sodium chloride decomposes into sodium and chlorine ions

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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Ammonia Experiments

Sunday October 31, 2010

Ammonia has been used by doctors, farmers, chemists, alchemists, weightlifters, and our families since Roman times. Doctors revive unconscious patients, farmers use it in fertilizer, alchemists tried to use it to make gold, weightlifters sniff it into their lungs to invigorate their respiratory system and clear their heads prior to lifting tremendous loads. At home, ammonia is used to clean up the ketchup you spilled on the floor and never cleaned up.

The ammonia molecule (NH₃) is a colorless gas with a strong odor – it’s the smell of freshly cleaned floors and windows. Mom is not cleaning with straight ammonia (it’s gas at room temperature because it boils at -28^oF, so the stuff she cleans with is actually ammonium hydroxide, a solution of ammonia and water). Ammonia is found when plans and animals decompose, and it’s also in rainwater, volcanoes, your kidneys (to neutralize excess acid), in the ocean, some fertilizers, in Jupiter’s lower cloud decks, and trace amounts are found in our own atmosphere (it’s lighter than air).

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Ammonia is a strong base – it combines with acids to form salts:

NH₃ + HCl –> NH₄Cl

But ammonia also can act as a weak acid. Remember, an acid is a proton donor, as in this reaction with lithium, where the ammonia molecule donated one hydrogen atom:

2 Li + 2 NH₃ –> 2 LiNH₂ + H₂

In this experiment, we make a stink and then we see something that will make us go ooooooh… and aaaaw. How fun is that? But you need to follow the instructions carefully and perform your experiment safely. Promise?

Ammonia will be generated by the combination of ammonium chloride and sodium carbonate. The amount of ammonia generated in this experiment is not a large amount. However, you really should experience this particular stink.

Materials:

3 test tubes and rack
sodium carbonate (MSDS)
ammonium chloride (MSDS)
copper sulfate (MSDS)
sodium hydrogen sulfate (NaHSO4) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
water
test tube stopper
measuring spoon
gloves, goggles

A chemical reaction is going to occur when the ammonium chloride, sodium chloride, and another chemical reaction is going to occur when the copper sulfate is added. These compounds are the reactants in our chemical reaction, and the blue liquid, CuCl (copper chloride), at the end of the experiment, will be our product. This experiment displays two types of reactions, a decomposition reaction when we combine ammonium chloride and sodium chloride, and a double replacement reaction when we add copper sulfate to the mixture.

C1000: Experiments 19-21

Download Student Worksheet & Exercises

When we combine ammonium chloride and sodium carbonate, ammonia will be produced. We will add copper sulfate to that mixture, producing two chemical compounds with totally different properties from those exhibited by the original chemicals.

Two chemical reactions will occur in this experiment:

(1) When you add ammonium chloride and sodium chloride to the water, a decomposition reaction will occur that produces ammonia gas, carbon dioxide gas, and sodium chloride dissolved in water. It is identified as a decomposition reaction because the reactants breakdown into elements or simpler compounds.

NaHCO₃ + 2NH₄Cl –> NH₃ + CO₂ + NaCl + 2H₂O

sodium carbonate + ammonium chloride –> ammonia + carbon dioxide + sodium chloride + water

(2) The next reaction takes place when copper sulfate is added to the sodium chloride and water. The products of this reaction are sodium sulfate and copper chloride (the blue color). This reaction is identified as a double replacement reaction due to the fact that the two reactants break apart and recombine, the reactants trading parts, recombining to form two other different compounds with properties completely different than those of the reactants.

NaCl + CuSO₄ –> NaSO₄ + CuCl

sodium chloride + copper sulfate –> sodium sulfate + copper chloride

Big suggestion here: All chemical vapors are best experienced by “wafting”, a procedure that brings the vapor to you, instead of sticking your nose in the test tube, bringing you to the vapors. Please get in the habit of smelling properly. If ammonia vapors can bring unconscious people back to consciousness, you should probably make sure you are sniffing safely.

Reminder: Always wash your hands or gloves, and your chemistry tools, when switching from one chemical to another to avoid contamination that could affect the experiment adversely.

Store: Put all chemicals away in their proper places to keep them organized and ready to be used again. All tools should be put away as well, but make sure hat they have been cleaned and dried before storing them. A rule of thumb in chemistry is always wash something three times.

Disposal: Pour liquids down the drain using plenty of water. Throw solid waste into the outside garbage to prevent filling the house with bad smells.

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Acids and Bases

Sunday October 31, 2010

This experiment is for advanced students.

ACID!!! The word causes fear to creep in and get our attention.

BASIC!!! The word causes nothing to stir in most of us.

The truth is, a strong acid (pH 0-1) is dangerous, but a strong basic (pH 13-14) is just as dangerous. In this lab, we will get comfortable with the basics of bases and the acidity of acids along with how you can use both and tell the difference between them.

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Familiar acidic solutions:

pH 1: Stomach acid
pH 2: Lemon juice
pH 3: Vinegar
pH 4: Soda pop
pH 5: Rainwater (serious acid rain could have a pH of 2-4)
pH 6: Milk
pH 7: Distilled water
pH 8: Egg whites
pH 9: Baking soda
pH 10: Antacid
pH 11: Ammonia
pH 12: Limewater
pH 13: Drano
pH 14: Sodium hydroxide (NaOH)

Materials:

Lemon
Apple
Blue litmus paper
White vinegar
Clear glass cup
Tartaric acid (C₄H₆O₆)
Measuring spoon
Measuring syringe
Water
Test tube rack
Test tube
Cool water
Sodium hydroxide (NaOH) (MSDS)
Dropper pipette
Calcium hydroxide (CaOH) (MSDS)
Erlenmeyer flask
Solid rubber stopper
Storage bottle
Stick-on label
Permanent marker

Acids usually taste sour and turn blue litmus paper red. There are exceptions. One exception to this is with apples. They contain malic acid. Malic acid does in fact taste sour by itself, but apples produce so much sugar that the sour taste of the acid is overpowered with sweetness. Making lemonade is a good example as well.

NaOH – Be very careful working with sodium hydroxide (NaOH). It isn’t an acid, so it shouldn’t be very harmful, right? WRONG! A strong base is just as dangerous as a strong acid. Please be careful when using them.

Don’t get confused and don’t forget what litmus paper indications mean. Acids turn blue litmus paper red, and bases turn red litmus paper blue. If you are testing a substance and the paper doesn’t change color, try the other type. The substance might not be neutral, but an acid or base that you used the wrong color litmus paper.

When testing with litmus paper, don’t dip the litmus paper into the chemical bottle. Use a clean dropper to transfer the chemical to the paper. Dipping into the chemical can and will, eventually, contaminate the chemical.

When shaking a liquid in a test tube or flask, put a solid rubber stopper on top. If you just start shaking from there, your stopper may fly across the room and scare your dog unnecessarily. The hot, or acidic, or basic contents of the container will find a place on the salad waiting to be served. The paramedics will be puzzled when they find the entire family, heads down, lettuce hanging from their mouths. With the stopper firmly inserted, wrap your hand around the container with your thumb over the stopper, pushing down to hold it in place while you shake.

After we finish the experiment, don’t discard the contents of the Erlenmeyer flask. It now contains limewater, a substance that we want to save for later experiments. Carefully pour the liquid into a storage bottle and discard the solids in the trash. Place a sticker on the bottle and/or use a permanent marker to label the bottle for future use. Keep the storage bottle out of direct sunlight when storing it.

We will explore for ourselves some of the properties of acids and bases. If we consider the acid-base theory discussed below, it will help us to further understand what we are experiencing in our lab.

C3000: Experiments 5-18

Download Student Worksheet & Exercises

Cleanup: We must clean everything thoroughly after we finish with the lab. After cleaning with soap and water, we need to rinse everything thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain, and solids put in the trash.

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Making Sodium Hydroxide

Sunday October 31, 2010

This experiment is for advanced students.

Ever use soap? Sodium hydroxide (NaOH) is the main component in lye soap. NaOH is mixed with some type of fat (vegetable, pig, cow, etc). Scent can be added for the ‘pretty’ factor and pumice or sand can be added for the manly “You’re coming off my hands and I’ll take no guff” factor. Lots of people still make their own soap and they enjoy doing it.

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One of the coolest uses for sodium hydroxide is in tissue digestion. By “tissue” we mean meat, bone, sinew…..meaning bodies! People who pick up dead animal (road kills) for the county dump their catch in barrels containing sodium hydroxide. The NaOH eats everything up and then the “sludge” is dumped in the landfill. They used NaOH to make them decompose. So this stuff is nasty and should never be touched with your bare hands!!

Materials:

Erlenmeyer flask
Alcohol burner
Lighter
Heating rod
Sodium carbonate (Na₂CO₃) (MSDS)
Calcium hydroxide (Ca(OH)₂) (MSDS)
Measuring spoon
Water
Tripod stand
Wire screen
Chemistry stand
Test tube holder
Test tube rack
Test tube
Filter paper
Funnel
Stock bottle for NaOH storage (MSDS)

Don’t inhale any fumes from reactions or powder welling out of chemical containers, especially calcium hydroxide dust. We want to test our product to see if it is NaOH. It should turn red litmus blue.

We will perform a bunch of operations in this lab.

Heating our calcium hydroxide / sodium carbonate mixture to create calcium carbonate and sodium hydroxide.
Filter out the calcium carbonate to collect the sodium hydroxide.
Test our sodium hydroxide product for the properties of NaOH.

C3000: Experiments 172-173

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Ca (OH)₂ + Na₂CO₃ –> 2NaOH + CaCO₃

Calcium hydroxide and sodium carbonate are combined in water and heated to produce sodium hydroxide and calcium carbonate

This is a double replacement reaction because the calcium ion and the sodium ion have swapped places

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids must be neutralized with vinegar, if a base, or baking soda, if an acid, before washing them down the drain. Before actually washing them down the drain check again with litmus paper to ensure that they have been neutralized. Solids are thrown in the trash.

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Potassium Permanganate

Sunday October 31, 2010

This experiment is for advanced students.

Potassium permanganate (KMnO₄) in water turns an intense, deep, purple. It is important in the film industry for aging props and clothing to make them look much older than they are.

Also, artists use it in bone carving. People who carve antlers and bone use KMnO₄ to darken the surface of the bone to make it look aged. They make the carving, soak it in potassium permanganate, then carve more, and repeat. The end result is a carving that has a light golden brown color. More dipping will darken the carving even more.

Potassium permanganate is going to undergo a chemical change with this activity. In this experiment, we will be able to witness several indicators of chemical change. Color changes, bubbles from gas generation, temperature change, and color disappearance are all indicators of chemical changes.

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Examples of chemical color changes we might be familiar with are autumn leaves changing color and a half eaten apple quickly turning brown.

Physical changes can mimic the indicators of chemical change, so we will need to always think through what we observe and then decide whether it is a physical or chemical change. Physical changes that mimic chemical changes can be color and temperature. The key is that physical changes are changes in state (solid, liquid, gas, sublimation) or changes in the condition of the material. In our pursuit of science knowledge, we will observe many physical and chemical changes. We need to be able to identify them accurately to really understand what is happening in an experiment.

Materials:

3% Hydrogen peroxide (KMnO4) (MSDS)
Test tube rack
2 test tubes
Potassium permanganate (KMnO4) (MSDS)
Sodium hydrogen sulfate (NaHSO4) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
Measuring syringe
Water
Measuring spoon
Solid rubber stopper

Always cap your chemicals after use and set them aside where they won’t get in the way. Your lab area should always be clear, clean, and uncluttered. Water and a fire extinguisher should be within arm’s reach. Always clean equipment before using any of it on another chemical.

Potassium permanganate is going to undergo a chemical reaction that will turn the deep violet or purple solution clear. It is a very cool experiment and looks like a lot of fun.

C3000: Experiment 102

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

KMnO₄ + NaHSO₄ + H₂O₂ = MnSO₄ + O₂ + NaOH + KOH

Potassium permanganate is added to sodium hydroxide, and then hydrogen peroxide is added and quickly capped.

MnSO₄ + O₂ + NaOH + KOH

The product of the reaction is manganese sulfate, oxygen, sodium hydroxide, and potassium hydroxide. The remaining chemicals are all clear, so the desired result is obtained.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain

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Potassium Hexacynoferrate (Reagant)

Sunday October 31, 2010

This experiment is for advanced students.

How do you know if your brother is stealing your candy? Unwrap a wrapped hard candy that he likes a lot. Roll the candy around in the powdered food dye that matches the candy. (Push the powder into the candy so it “disappears”.) Re-wrap the candy. Set the candy in the place where it usually disappears from. Wait ten minutes after the candy disappears. Find your brother. He will be sporting a new color on his hands and mouth. Dye is hard to remove. It will have to be worn every day at school until it fades away as the skin cells slough off. The dye he now wears is in indicator that he has been taking your candy.

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Did you guess that this lab is about indicators? A reagent is chemical compound that creates a reaction in another substance; the product of that chemical reaction is an indicator of the presence, absence, or concentration of another substance.

Your brother’s situation is not a chemical reaction, but a reaction will be observed in his looks and his mood.

We are going to prepare copper sulfate and ammonium iron sulfate solutions and test them to see if our reagent, potassium hexacynoferrate II will cause chemical changes that indicate that copper is present in one, and iron is present in the other.

I’m sure your brother will stay far away from your candy from now on. I know this is obvious, but don’t eat anything in this lab or use it to coat candy… that was just an example to illustrate what an indicator is and how to use it.

Materials:

Erlenmeyer flask
Water
Potassium hexacynoferrate II K₄Fe(CN)₆ (MSDS)
Copper sulfate CuSO₄(MSDS)
Measuring spoon
Solid rubber stopper
Test tube rack
3 Test tubes
Measuring syringe
Small labeled container for NaOH
Dropper pipette
Ammonium iron sulfate NH₄Fe(SO₄)₂(MSDS)
Sodium hydroxide NaOH (MSDS)

We need to remember to only make as much Potassium hexacynoferrate II as we need. Label test tubes with contents information clearly visible. Always remember that when the term “reagent” is used in chemistry it is referring to an indicator chemical.

We will put together two solutions with metallic chemicals dissolved in water in each. Let’s pretend we have no idea if they are metallic or not. Many times as a chemist, when analyzing a customer’s of a production chemical, we are looking for metal in a solution as an indicator of something good or something bad. If one of the factory’s systems contains a corrosive liquid flowing through its veins, it would be good to know if some metal somewhere is corroding, being dissolved, by the fluid. Our tests could confirm a problem or set the boss’s mind to rest….and get us a big bonus if we save the day.

C3000: Experiments 260-264

Here’s what’s going on in this experiment:

In test tube #1: Copper sulfate solution into which we added Potassium hexacynoferrate II. A color change occurred (brown) and a precipitate fell out of the liquid to rest on the bottom of the test tube. This reaction was an indicator for the presence of metal.

In test tube #2: Ammonium iron sulfate solution into which we added Potassium hexacynoferrate II. A color change occurred (dark blue). This reaction was an indicator for the presence of metal.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids, after neutralization, can be washed down the drain. Solids are thrown in the trash.

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Iron Sparklers

Sunday October 31, 2010

This experiment is for advanced students.

Sparks flying off in all directions…that’s fun. In this lab, we will show how easy it is to produce those shooting sparks. In a sparkler you buy at the store, the filings used are either iron or aluminum.

The filings are placed in a mixture that, when dry, adheres to the metal rod or stick that is used in making the sparkler. The different colors are created by adding different powdered chemicals to the mixture before it dries. When they burn, we get red, blue, white, and green.

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Materials:

Card stock
Alcohol burner
Iron filings
Gloves

It’s tempting to use a handful of filings to produce a literal shower of sparks. The effect is actually better with small amounts. To accomplish anything with a large pile of filings would require you to blow REALLY hard to make a filing cloud that will combust well. A larger reaction means more sparks flying around. The amount of filings recommended in the lab is a safe amount. Increasing the amount used increases the danger. You could take an interesting, fun, and safe lab and transform it into something that burns the hair off your arms. Besides, burning hair doesn’t smell good.

Here’s what’s going on in this experiment:

Iron + Oxygen –> Iron Oxide

Iron and Oxygen are burned to produce Iron Oxide

This is the balanced chemical equation: 2Fe + O2 –> 2FeO

C3000: Experiment 54

Download Student Worksheet & Exercises

Handling iron filings is not dangerous. Minor things that can occur, such as: Iron filings can stain your skin gray; if there is a large filing in your container, rubbing your finger against it could give you a painful splinter.

Return unused filings to your container. Any surface these filings touch turns gray, so keep your filings corralled. Cleaning your work surface with a wet paper towel is the easiest way to clean up.

Discard any unburned iron powder that is coating the area around your alcohol burner into a trash container outside. It is not toxic, but still….don’t use chemicals or experiment residue as a snack. Never a good idea.

What is going on here? When you build a campfire at the campground, why doesn’t the grill spark and burn up? The grill is iron, the filings are iron, and there is always oxygen available in the air. What’s the deal here? Combustion needs two things, fuel and fire. Not enough of either and nothing will burn. But a woodstove is made up of a lot more iron by weight than that little scoop of filings. It has to do with surface area. Take an equal weight of solid iron and iron filings. Put a match to the solid iron and all it gets is hot. Blow the same weight of iron filings into the flame and POOF! The key is surface area. Surface area can affect the way a chemical reaction occurs, and in this case, whether or not it occurs at all.

To better understand the effect of surface area, eat some candy! Put a whole Lifesaver candy in your mouth. Suck, move your tongue all over it, swish it back and forth in your mouth. You are not allowed to bite or swallow it. How long does it take to completely dissolve? Do the same thing with another Lifesaver broken into pieces. Which dissolved faster? The same thing happens with the iron. The smaller the pieces, the easier it is for the iron to burn. When you blew iron filings into the air above the flame, you increased the surface area even more by increasing the air space between the particles. An increase in surface area always makes things happen faster. Granulated sugar dissolves faster than sugar cubes, and a piece of wood burns faster after you chop it into kindling. Pay attention and you will notice other situations where increasing surface area speeds up physical changes and chemical reaction times.

An additional experiment that you can try on your own is burning steel wool. Properly prepared ahead of time, steel wool will spark as it burns up. A great emergency fire starter is a 9V battery and steel wool. Fluff up the steel wool and touch a portion of it across the terminals of the battery. The steel wool will burn just like it did with a match.

Steel wool is just a ball of really long iron filings. If you fluff out the steel wool and light it, it burns easily. If you do try this, do it outside over the lawn or an area of dirt. At some point in the combustion you will want/need to drop the steel wool or get your fingers singed.

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Iodine

Sunday October 31, 2010

This experiment is for advanced students.

In gas form, element #59 is deadly. However, when iodine is in liquid form, it helps heal cuts and scrapes. The iodine molecule occurs in pairs, not as a single atom (many halogens do this, and it’s called a diatomic molecule). It’s hard to find iodine in nature, though it’s essential for staying healthy… too little iodine in the body takes a heavy toll on how well the brain operates.

A chunk of iodine is blackish-blue, and will sublimate (go from a solid straight to a gas, as seen in the photo here). Iodine is the heaviest element needed by living things. Iodized salt is sodium chloride fortified with iodine to prevent people from not getting enough iodine in their daily diets.

Iodine is found in seaweed (kelp) and seafood as well as vegetables that are grown in dirt that has high iodine levels. People that live inland and do not eat fish often have lower iodine levels than their coastal, fish-eating neighbors. The trick is not to get too much or too little iodine in your diet, because the symptoms of deficiency and excess levels are quite similar.

Starch (like cornstarch) are used as an indicator for detecting iodine in chemistry experiments. When combined with iodine, starch forms a blue-black color in the solution. We’re going to do this and many other activities in this lab, because this experiment is actually several labs rolled into one. First, we have to make iodine, store it, and then we get to use it in several experiments. Are you ready?

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Materials:

Goggles
Gloves
Glass jar
Chemistry stand
Test tubes
Test tube holder
Measuring spoon
Corn starch peanut
Water cup
90 degree bend glass tubing
One-hole rubber stopper
Paper towels
Stain-free work surface
Solid rubber stopper
Denatured alcohol
Dark brown glass storage bottle for iodine
Dropper pipettes
Alcohol burner
Lighter
Measuring syringe
Water
Potassium iodide KI (MSDS)
Potassium permanganate KMnO4 (MSDS)
Sodium hydrogen sulfate NaHSO4 (MSDS) AKA: Sodium Bisulfate Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.

Remember that iodine is toxic paper and harmful to the environment.
Safely shake test tube to homogenize chemicals using a solid rubber stopper and dispose of in the outside trash.

NOTE: Heat slowly and carefully. You don’t want your test tube in the flame. The end of the glass tubing should not extend into the alcohol. From time to time, touch the end of the glass tubing to the alcohol to rinse iodine from the tube into the alcohol, but the glass tubing shouldn’t reside in the alcohol. Conduct this experiment outdoors or in an extremely well ventilated area inside the house.

Follow cleanup instructions carefully for safety. These are very toxic substances we are working with.

As heating progresses, purple gas will form in the upper test tube. A brown color will begin to form in the alcohol. Heat until purple smoke disappears from the upper test tube.

C3000: Experiments 139-149

Here’s what’s going on in this experiment:

2KI + KMnO₄ + NaSO₄ + H₂O–> I₂ + MnO₂ + KOH +KIO₃ + Na₂SO₄

Potassium iodide and potassium permanganate and sodium sulfate and water are heated to produce free iodine gas and magnesium oxide and potassium hydroxide and potassium iodide and sodium sulfate.

All this to produce the iodine we need for the next several experiments.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids need to be filtered through a paper towel and washed down the drain with plenty of water. Solids are thrown in the outside trash.

Going Further

*Save all solutions you make in these experiments. You will use them in the other experiments.

Testing Iodine solution

After the drops of iodine are in the test tube with water, observe. Any solid particles in the test tube prove that our iodine is not soluble in water.

Addition with Iodine

Using the solution from the above experiment, adding KI will dissolve all the solids that were observed. Why did the solids disappear? Well, nothing dramatic was seen, but an addition compound was created.

I₂ + KI –> KI I₂

Sodium Thiosulfate

Sodium thiosulfate (Na2S2O3) solution is pipette drop by drop to above solution until it turns clear. The reaction that takes place turns our solution into sodium hypoiodite (NaOI)

Packing Peanut

We fill a glass jar with water and 10 drops of iodine and mix well. The water will be a pale brown. Dissolve a corn starch peanut in water. When we add starch solution to the iodine and water, the water turns clear, then blue. We have just created iodine starch!

Colorless Iodine

Sodium thiosulfate solution from an experiment above. Put a few droppers of this solution into the iodine starch and stir. Colorless! We have a colorless iodine solution….very cool!

Iodine and Heat

To set this one up, dropper one drop of iodine solution into a test tube half-filled with water. Then we regain our bright blue color by adding our starch solution to the iodine water.

When we add heat, The solution turns clear! But, we’re not done. The test tube goes into a half full jar of cool water. The solution in the test tube is turning blue. If you keep doing these actions over and over again, you will keep getting the same results.

Did you notice something? The reaction is ________. Think, now.
(Psst! It’s reversible!)

Colorless Iodine Without Heat

In this experiment we use alcohol to achieve a clear solution. We pour some iodine starch solution into some alcohol and the solution turns clear. The alcohol removed the iodine from the solution.

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How to Get Hydrogen from Zinc

Sunday October 31, 2010

This experiment is for advanced students.

Zinc and Hydrogen are important elements for all of us. Zinc (Zn) metal is element #30 on the periodic table. Lack of zinc in our diets will delay growth of our bodies and can kill.

Hydrogen gas (H) is element #1 on the periodic table. Hydrogen was discovered in the 1500s. In a pure state, hydrogen combustion (in small quantities) is interesting. In large amounts, mixed with oxygen, the explosion can be devastating.

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We are going to perform an experiment that generates a small amount of hydrogen gas, with a correspondingly small explosion. Hydrogen is violently flammable in air, but by itself….not so much. Hydrogen is lighter than air, so has been used in airships, or blimps. The Hindenburg, a German airship filled with hydrogen, burned up quickly on May 6, 1937 while tied to a mooring mast.

Currently, hydrogen is being thought of as the “fuel of the future” for our cars and other vehicles. Most the Earth’s our hydrogen is contained in water (H₂O). Most of the experimentation has been in producing hydrogen through electrolysis. That proves very expensive to produce and transport. Until a cheaper alternative appears, hydrogen (H₂) is not a practical alternative.

Scientists are lately giving a lot of attention to a process that will produce hydrogen cheaply and easily. That method is to heat zinc powder in the presence of air (oxygen). It can be achieved at low temperatures, little cost, and little danger – perfect for a hydrogen fuel cell in our car. Don’t go filling your tank with it right away, though. Engineers still need to work some bugs out. It will happen soon, so be patient. (And remember, you saw it first in your chemistry set!)

Materials:

Gloves
Goggles
Chemistry stand
Zinc (Zn) powder (MSDS)
Measuring spoon
4 test tubes
Test tube holder
Alcohol burner
Lighter
One-hole rubber stopper
Rubber tubing
90⁰ bend glass tubing
Water
Measuring syringe
Stirring rod
Clear pan

Important! Dispose of the Zinc (Zn) left in the test tube in the outside trash. Accidentally ingesting (and it should only be accidental) of Zinc (Zn) or Zinc Chloride (ZnCl), will harm you or animals. It will not be one of your best days. Call 911 if this happens.

After you have finished your experiment, be careful of the hot test tube containing the zinc compound. The test tube is very hot, and there will be a difference in pressure between the water tank and the test tube. Because the test tube has been heated, the pressure is less than atmospheric pressure.

As it cools, the water in the tank, which is at atmospheric pressure (the pressure of the air in the room) is higher than in the test tube. The test tube’s low pressure is looking to suck something, anything, up the glass tube. The water, sitting there at normal air pressure, notices the need. Water climbs up the tube in response to the test tube’s request.

At the conclusion of the experiment, with the heat off, the test tube starts to cool and water then donates some stuff to equalize the pressure. If allowed to , that cool water hits that hot zinc, or hot test tube, and the test tube could explode and the zinc could quickly react, blowing out the stopper and spewing hot zinc all over you.

Here is the safety information for the products in this chemical reaction:

Zinc Oxide (MSDS)
Hydrogen (MSDS)

You first put zinc powder and water together in the end of the horizontally held test tube. But why place a pile of, dry zinc, laying in the test tube near the wet zinc? We want to create a chemical reaction with zinc and water. Wet zinc powder in the end of the test tube allows the dry zinc to come in contact with water when they are both heated without the powder actually getting wet. This way the reaction occurs faster and more efficiently. We don’t have to wait any longer than necessary this way.

C3000: Experiments 67-69

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

In this experiment we are causing a single replacement reaction to occur between zinc powder and water. In a replacement reaction, a compound breaks down into its elemental parts in the first stage of the chemical reaction. A new compound is created as the elements search about for something to bond with to satisfy their needs to gain or give up electrons.

Zn + H₂O –> ZnO + H₂

Zinc powder reacts with water under the influence of heat to become zinc oxide and hydrogen gas. The new compound is called zinc oxide (ZnO).

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the outside garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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Latest News

Worm Column

Garden Worm Tower

Build your own worm farm and watch them turn food scraps into soil!

Earthworm Dissection

NEVER pick wild mushrooms! In addition to the uncertainty in the type of mushroom, there’s also possible harmful bacteria growing on the mushroom.

Grow Your Own Bacteria

What's happening?

Is it safe to wash my hands in water?

Is soap better than sanitizer?

How to Grow Your Own Bacteria

Finding Bacteria in Yogurt

Bacteria are classified as follows:

Build an Ecosystem

Fun with Yeast

More Ideas!

Tracking Plant Growth

Carnivorous Greenhouse

Grafting

Hybridization

Transgenics

Step one: Creating the Parent Generation

Step two: The Child

Step 3: What the Child Looks Like

Step 4: Make another family and compare!

Conclusions:

Extra credit:

Experiment #1: Water moving INTO the carrot via osmosis and UP the carrot.

What’s going on?

Procedure:

What’s going on?

Experiment #2: Water moving OUT of the carrot via osmosis

Procedure

What’s going on?

Questions to Ask:

Chemical Data & Safe Handling Information Sheet

C1000: Experiments 1-10 C3000: Experiments 5-18

Going Further

C3000: Experiment 64

C3000: Experiment 51

C3000: Experiment 74

Going further: Elephant’s Toothpaste

C3000: Experiment 58

C3000: Experiment 76-78

C3000: Experiment 83

C3000: Experiments: 105, 110

C3000: Experiment 31

C3000: Experiment 53

C3000: Experiment 52

Magnesium Battery

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet. Handle this chemical only with gloves, and be sure to read over the MSDS before using.

C1000: Experiment 75 C3000: Experiment 295

C3000: Experiments: 36,60

C1000: Experiment 74

C3000: Experiment 121, 289

Here’s the breakdown of the entire process:

Going Further

C1000: Experiments 66-70

C1000: Experiments 19-21

C3000: Experiments 5-18

C3000: Experiments 172-173

C3000: Experiment 102

C1000: Experiments 1-10
C3000: Experiments 5-18

C1000: Experiment 75
C3000: Experiment 295