Aim

Observe that air expands on heating.

Materials Required

1. Two beakers
2.  A test tube or an empty plastic bottle
3.  a balloon
4. cold water
5. hot water

The Procedure

1.  Inflate the balloon slightly and fix it on the mouth of the test tube (or a bottle) tightly with a thread. (It is advisable to inflate and deflate the balloon a few times.)
2. Pour hot water into one beaker and cold water into the other beaker.
3. Place the test tube with the balloon in cold water.
4. Observe the size of the balloon.
5. Transfer the bottle now to the beaker containing hot water.
6. Observe the size of the balloon again.
7. Transfer the bottle back to cold water and observe the size of the balloon once again.

Simulator Procedure

1. Take the test tube with the balloon.
2. Place the test tube in one of the beakers containing either hot or cold water.
3. Observe the size of the balloon.
4. Transfer the test tube with the balloon to another beaker.
5. Observe the size of the balloon again.

Observation

• Balloon gets inflated in hot water and deflated in cold water.

Conclusion

• There is air inside the empty bottles or a test tube. When the test tube is kept in hot water, the air inside it gets heated. It expands and inflates the balloon.
• In cold water, the air in the bottle contracts and the balloon is deflated.
• That is, the air expands on heating and contracts on cooling.