Friday, October 24, 2014

thermodynamics - Why did my liquid soda freeze once I pulled it out of the fridge?


Can someone explain in both layman's terms and also technically why when I pulled my glass filled with liquid soda from the freezer, the liquid soda quickly froze?


Doesn't this violate the 2nd law of thermodynamics since heat moved away from the glass with soda and to the ambient?



Answer



Your soda was in a supercooled state. Being in the freezer, it was at a temperature below its freezing point however it remained as a liquid as the glass was too smooth to allow ice crystals to start to form (in technical terms, the phase transition requires a nucleation site). When you removed it from the freezer, you gave it the disturbance necessary to catalyse the transition from supercooled liquid into a block of ice. No violation of the 2nd law occurred.


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