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)
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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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where is the worksheet for this lesson?