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Q & A: Exploding Film Canisters!

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Most recent answer: 10/22/2007
Q:
why does a film canister shoot in the air when you dissolve an effervescent pain tablet in it
- james hatfield (age 11)
matewan middle school, matewan, wv usa
A:
ames -

I think the activity you're refering to is this: Take a film canister and put some water in it. Drop an effervescent pain pill (like Alka-Seltzer) in and close the lid. Keeping the canister pointed away from you, the lid should pop off and go flying into the air.

The reason for this is a chemical reaction between the pill and the water. Pain pills like this contain a chemical called sodium bicarbonate (also known as baking soda). When the sodium bicarbonate reacts with water, it forms carbon dioxide, which is a gas. Gases like carbon dioxide take up a lot of space, so the lid is pushed off of the container to make way, sending it flying!

-Tamara

(published on 10/22/2007)

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