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)

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.

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

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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