Boyle’s Law in a Bottle experiment

Materials: Balloon, Straw, Bottle, Safety goggles & Fizz-keeper

Safety Precautions: Wear safety goggles. To avoid over pressurizing the bottle, do not pump up the bottle with the fizz-keeps more than 100 times. When releasing the pressure, unscrew the Fizz-Keeper slowly from the bottle. Never aim the Fizz-Keeper at another person, and never place your face directly over the Fizz-Keeper, especially when unscrewing it from the bottle. Never use the Fizz-Keeper with a glass bottle.

Procedure:
Blow up balloon inside of a 2-liter bottle and tie it off. The balloon can be of any size. You must insert a straw next to your balloon as you blow it up inside the bottle.
Now screw on the Fizz-Keeper and pump up the bottle with air. DO not pump the Fizz-Keeper more than 100 times. Observer
Unscrew the Fizz-Keeper slowly from the bottle and watch what happens.

Explanation
This experiment is a perfect illustration of Boyle’s law, which states that as the pressure on a gas increases, its volume decreases. As the bottle filled with more air, more molecules collide with the outside walls of the balloon, causing the balloon to shrink.

As for the expansion in volume when the Fizz-Keeper is released, Boyle’s law also states that as the pressure exerted on a gas decreases, its volume increases. As the compressed air with in the bottle escapes, the pressure on the balloon decreases. This causes the balloon to expand to its original volume. Notice that the balloon does not expand indefinitely, however. Since Atmospheric pressure is still being exerted on the balloon at a pressure of about 14.7 pounds per square inch (psi), the volume of the balloon is kept in check.