High and Low Air Pressure

Ken Karp Photography

• 2 L plastic bottle, or vacuum chamber and vacuum pump

• warm tap water

• long safety matches

1. Put a small amount (about 15 mL) of warm water into the plastic bottle.

2. Light a match. Blow it out and then hold it inside the bottle to collect some smoke. Quickly remove the match and put the cap tightly on the bottle. Shake the chamber to add moisture to the air inside.

3. Squeeze the bottle and release. Pump a few times while observing the air inside the bottle.

4. Repeat the experiment, but this time use 10 mL of cold water. Next, repeat the experiment with a dry bottle. Do not add water. Just create smoke, close the bottle, and squeeze and release.

1. What did you observe inside the bottle when you squeezed and released the bottle?

2. What happens to the pressure, volume, and temperature of the air inside the bottle when you squeeze it? When you release it?

3. What gas law best explains how the properties of the gas inside the bottle change during this experiment? Explain your choice.

4. How does this gas law explain what’s going on in the bottle?

5. What did you observe when you used a dry bottle?