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Q & A: Pepsi blowing up

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Most recent answer: 10/22/2007
Q:
Why does a can of pepsi blow up if it is left in the freezer?
- kevin (age 14)
moanalua HS, hawaii
A:
Pepsi's made up mostly of water. The next most important ingredient is sugar, and then carbonic acid (which makes carbon dioxide, the "fizz"). Water expands when it freezes (and also the solubility of the carbon dioxide decreases, but I suspect the water expanding is more important here). The can doesn't expand when it gets cold -- instead it shrinks. The volumeof the stuff inside the can tries to go up while the can tries to shrink, so the pressure builds up until .... BAM! Slushy Pepsi all over your freezer.

Tom

(published on 10/22/2007)

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