Coin poppers are a brilliant experiment to demonstrate air pressure!
What you need
A small empty plastic drink bottle
A 2p coin
A small square of kitchen roll
1. Put the empty bottle in the freezer for about an hour to cool.
2. Cut a small square of tissue paper and put it on top of the 2p piece
3. Pour a little water over the tissue to stick it to the 2p
4. Without removing the bottle from the freezer, place the 2p on top of the bottle, tissue side down, to seal as a lid.
5. Leave for half an hour
6. Bring out and warm the top of the bottle with your hands!
7. Watch the magic!
Why does this work?
We assume we have put an empty bottle inside the freezer, but of course, it is actually full of air which is a mixture of gases containing nitrogen, oxygen and carbon dioxide, amongst others. As the gas cools, it shrinks, lowering the pressure, but because the lid is off, more air can enter the bottle from the freezer. Once you placed the coin lid on, you have sealed the top. As the air inside warms up again from your hands, it expands and forces more pressure on the inside of the bottle and the lid, compared to outside the bottle. It creates enough pressure to break the seal and pop the lid!
Last Updated on April 3, 2023 by Emma Vanstone
This looks like fun! Can you tell me which United States coin would be the same size as a 2p coin?
I think a quarter would be the nearest. x
maryanne @ mama smiles
Very cool! And an experiment I haven’t seen before!
Glad you like it!
how cool – I know a certain 7 year old who is just going to LOVE this!
Yay, let us know how you get on!
Cool! I just tried this at home! and I don’t have small children as an excuse!!! tee hee
Did it work?
Very cool! Literally. I think we need a bigger freezer!
🙂 Let us know if you try it!
Great idea. Am now going to follow and get some more great stuff for the kids (ps came over from the blohop at Mummy’s little monkey!)
Very cool! I had never seen this before. Thanks so much for sharing with Tuesday Tots.