Why does a soda, that is still a liquid, freeze after you take it out of the freezer and pop the top?

Answer 1

There are equations generally described as Equations of State which describe the relationship between pressure, temperature, and volume. One particular one deals with ideal gasses, like the carbon dioxide within the soda contained in a soda can. This equation is:

PV = nRT
n and R are generally constants determined by the materials involved.
P ==> Pressure
V ==> Volume
T ==> Temperature

This equation tells us that if volume is held constant (like inside the soda can), and you suddenly lower the pressure (like when you open the can), then the temperature will decrease. If the inital temperature is just above the freezing point, then when the temperature lowers from the pressure being reduced, the remaining liquid may freeze.

Answer 2

I don't know why this happens, but you should try it with cider, It makes a nice appley alcaholic slushy. And watching it freeze as you pour it into a glass is cracking entertainment (once youve had a few).

Just had a thought- could it be to do with the evaporation of the dissolved gasses cooling the liquid further once the bottle is open?

Answer 3

the cooling affect comes from the evolution of the gas

when you release the pressure off the beverage by opening the lid, those gasses expand and some of them leave solution

gas expansion and undisolving require heat, the heat is taken from the surrounding area, mostly the beverage itself, causing a very quick but short lived cooling that can "slush" a drink that is already near its freezing point

this phenomena is similar to the way water evaporating off you body (as when you come out of the shower) will cool you, or a very volatile material like gasoline will cool you if you get some on you (because it is evaporting quickly and pulling heat from you)

the freon cycle in an air conditioner takes advantage of a similar phenomena by pulling heat from the air in the home (or car or whatever) to boil the freon when the pressure is taken off the freon (like opening the beverage bottle)

Answer 4

I have had this happen many times, I'm no chemist but I think when it cold liquid hits the warm air it causes this.