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2. Crash Bang! – Exciting experiments for you to try at home…
De-Fizzing a Soda Can
Yet another fizzy drinks activity. Maybe it’s best to try this outside...
What you need
 An unopened can of soda - the warmer the better
A finger
Optional: a pencil or other tapping utensil
 What to do
1) Shake, shake, shake your can of soda (or simply use a can that has fallen or has been shaken accidentally).
2) Place the can on a tabletop and tap the sides of the soda can with your finger (or a utensil). Rotate the can as you tap. Five to ten raps on the side of the can should do it.
3) Wait a few seconds.
4) Point the mouth of your can away from your body, anyone else's body, and any thing that you don't want spritzed with soda. Open the can and see what happens.
5) Option 2 - try this with two cans of soda, side by side, both shaken but one tapped and one not.
What's happening?
When you opened the can, did the soda spray out of it? If you tapped the can it shouldn't have. However, if you didn't tap the can...watch out! The soda probably spewed out!
Carbonated drinks in a can are under pressure and contain a dissolved gas called carbon dioxide. At normal drinkable temperatures and atmospheric pressures this dissolved gas wants to leave the liquid. As it does, it makes tiny bubbles in your glass and when you drink the soda, these bubbles give you that tongue tingling sensation.
If the can has been shaken (particularly if it is warm) bubbles get trapped in the liquid, attached to the walls and bottom of the can. Tiny bubbles of carbon dioxide attach to these larger bubbles and the result is a drink / bubble mix. Opening immediately can have horrible consequences as these bubbles grow rapidly when the pressure is released. They rush to the surface bringing the liquid with them.
You can just wait before opening your can or tap. Waiting awhile gives carbon dioxide bubbles time to re-dissolve into solution. Tapping however allows the bubbles to detach from the sidewalls and bottom of the can so they can float to the top (Step 3, where you waited a few seconds, is where you gave time for the bubbles to float upwards). There they meet the largest, but most benign bubble of the bunch - the one right under the lid.
Special Safety Advice
Be careful not to spray fizzy drinks into your, or other people's, eyes.
This activity came from the Wild West Fizzout activity on the Scicast site. There are some fantastic films on there - why don’t you have a go and make one yourself?
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