Air Takes Up Space - Balloon in a Bottle

The goal of this experiment is to show that an "empty" pop bottle is not really empty. It contains air and air takes up space.

 

Materials

2 Liter plastic pop bottle

2 Liter plastic pop bottle with hole in side

Balloon

 

What To Do

Ask students what happens when air is blown into a balloon. Ask them to predict what will happen when air is blown into a balloon in a bottle. Push the balloon into the bottle without a hole and spread the small open section of the balloon over the mouth of the bottle. Try blowing up the balloon. Ask students to explain what they observed. Now use the bottle with the hole in the side. Ask students to predict what will happen when air is blown into the balloon this time. Try blowing up the balloon again. 

 

Questions

1. Have a student put his/her hand near the exit hole of the bottle when another student is filling a fresh, clean balloon with air. What is escaping the bottle?

2. What does this experiment teach us about air?

 

Summary

It is difficult to blow up the balloon initially because the air trapped inside of the bottle is taking up space inside the bottle. For the balloon to expand into the bottle the air in the bottle must be compressed to allow space for the balloon or the air must be able to somehow exit the bottle. By using a bottle with a hole in the side, air is allowed to escape from the bottle as the balloon is blown up.

 

Sources

"Teaching Chemistry with Toys: Activities for Grades K-9." McGraw-Hill, Terrific Science Press, 1995. ISBN: 0-07-064722-4

© S. Olesik, WOW Project, Ohio State University, 1999.