You often have to blow hard to inflate a balloon on birthdays or any other occassion. But in this experiment you will perform & see how a balloon inflates on its own.


Supplies Needed
  • A small party Balloon
  • One small bottle
  • A kettle
How to do

1. Boil the kettle. 

2. Add 1 tablespoon of water from the kettle into the empty bottle.(The above 2 steps should be done by adults or under strict adult supervision)

3. The bottle will be very hot and full of steam at this point. 

4. After 20 seconds stretch the opening of the party balloon over the mouth of the bottle. Now stand back let the bottle cool off with the balloon covering the opening. 

What do you observe?

As the bottle cools, the balloon gets sucked into the bottle. If you had just the right amount of water left when you put the balloon on the bottle, the balloon will actually inflate into the bottle until it fills the whole of inside.

Why is it happening ?

When the water boils, it becomes steam. As the water boils away, the steam fills the whole inside of the bottle. If you had just taken the bottle and set it on the table to cool without adding the balloon, the steam would have cooled and condensed back into a very small amount of water. The water occupies lesser space than steam so air is needed to fill the gap. This comes through the open bottle neck.

What you did in this experiment was put a rubber balloon in the way of the air trying to get back in the bottle and the balloon is pulled inside instead. 

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