Can You Blow Up a Balloon in a Bottle?



 

This super-simple experiment, originally from the Questacon Science Club, might stump even the smartest of adults!

Here’s what you’ll need:  a balloon, a 2-liter plastic bottle (I used a 16 oz. bottle, but the 2-liter will work better), a thumbtack, and a nail.

Begin by asking the following question:  Can you blow up a balloon inside a bottle?

Try it out…

1. Put your balloon into the top of your bottle and stretch the neck over the bottle opening. Try to blow the balloon up while it is still in the bottle.

Does it work?

Nope, the balloon will barely budge.

Try this…

Use a thumbtack to puncture a hole in the bottom of your plastic bottle. Use a nail to make the hole larger, to there it is at least 1/4 inch in diameter.

Again, place the balloon in the top of the bottle and stretch the neck over the bottle opening. Try blowing it up again.

It worked!

The Science Behind It:

In order for a balloon to blow up, you must force air inside it. However, when you try to blow the balloon up inside an “empty” bottle, you can’t because the bottle is actually already filled with air! Our lungs don’t exert enough pressure to force the air out of the bottle. Once you poke a hole in the bottle, some of the air can escape as you blow more air into the balloon!

 

You could also do what Questacon Science Club did and trick a friend with this experiment. :)

 

Find this experiment and many more in my FREE Fascinating Science for Kids eBook!

 

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7 Comments

  1. My son did this with his grandmother as a joke over the summer. Her bottle didn’t have holes and his did. It made for a fun blog post for him.

  2. Thanks to all the people who work here because we really needed an idea for our school science expo project. This website was perfect because it had the science behind it as well!! Thanks so much!!

    Regards, Hannah Chow & Isabella GU :D

    PS We are in year 4.

    KEEP PUTTING AWESOME SCIENTIFIC EXPERIMENTS ON THIS WEBSITE!! THANKS AGAIN!

  3. Put a straw in the neck of the bottle, but outside the neck of the balloon. That allows the air to escape from the bottle as you blow up the balloon. Pull the straw out when the balloon fills the bottle.

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