So, I caught myself gently pouring a can of soda into a cup of ice (making sure that there was room for air to move through so the stream of soda from the can to the cup was consistent and even) instead of just haphazardly tilting and dumping the entire thing in there as quickly as possible. I was doing this in part to prevent spills at my desk, but also to keep the carbonation present in the soda. This got me wondering: why does pouring soda quickly cause it to fizz more and lose carbonation?


1 Answer 1


Because your soda is a supersaturated solution of $\ce{CO}_2$, and such solutions are non-equilibrium and hence unstable. Any physical disturbance (shaking, touching a rough surface, etc.) causes it to emit the gas and return to equilibrium state. Throw in some salt, and you will see a reaction even more vigorous.

Supersaturated solutions of solid compounds exhibit similar behavior, but they are not that easy to come by (I mean, starting from the typical household items). Sugar solution is too viscous, and table salt is no good because its solubility does not depends on temperature all that much, so you can't really supersaturate it.

There is, however, another pretty common example of non-equlibrium state, and that is superheated water. If you pour some bottled water into a clean cup, heat it in a microwave for a while, and then touch it not too gently, it may almost literally explode in your face, so beware.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.