Question

What is meant by saying that air expands on heating? Support your answer with the help of an activity.

Answer 1

When air is heated, the molecules of hot air move faster than particles of cold air and move further apart from each other. Hence, we say that air expands on heating.

Activity:

Take a balloon and press it flat so that there is no air inside it. Take an empty bottle and tie the balloon around it with the help of a rubber band so that the air doesn't escape from the bottle. Take water in a beaker and boil it. Place the bottle in the boiling water and observe.

Observation: We observe the balloon is inflated.

Inference: The air in the bottle was heated by boiling water. This heat caused the air to expand inside the bottle and further move and enter into the balloon, thereby causing it to inflate.

Conclusion: Air expands on heating.