I must have been stoned the day they talked about this in 6th grade science class, because I’m thinking I should know this:
Put a bottle of beer in the freezer. Leave it there just a little to long. Take it out. Ahh, good, it’s not frozen. The beer is still liquid. You can see through the bottle. It’s still liquid. You open it up…FRRRRUMP. The liquid turns into hard ice. Why?
Has to have something to do with the outside air hitting the liquid, but what are the mechanics of this? Why/how does this happen? Why does it remain liquid until the cap is twisted off, then turns into ice?
This only works because the beer is carbonated. When you remove the cap, you release the pressure inside, and allow small bubbles to form. The beer’s temperature is below freezing, so ice crystals form around the bubbles.
I would guess that its because of the high pressure of bottling and the fact that the beer is mostly water. Unlike most liquids, water has a greater volume when in solid form. When sufficient pressure is applied on the beer, it take much more cooling to reach the solid state (if pressure is high enough, it may not freeze at all). Thats why its not frozen when you pull it out of the freezer uncapped. Release the pressure by upcapping it and suddenly the beer doesn’t need as much cooling to freeze. If i’m right, then this should technically work w/ any well sealed bottle of water.
I would have thought it is because the beer was not quite at its freezing point yet and releasing the pressure allowed it’s temperature to drop suddenly below freezing. I seem to remember that temperature and pressure are directly related, though I can’t remember whose law that is. This is, I think, why a can of compressed air gets colder as you use it.
It’s early … maybe that’s what y’all said and I misunderstood it…
As far as beer is concerned, first of all there’s the fact that aolcohol lowers the liquid’s freezing point. The more alcohol, the lower the temperature must be for ice to form.
Ever try freezing Vodka? I rest my case.
Second, yes, the pressure in the bottle also serves to lower the freezing point. Just as the pressure in a car radiator raises the boiling point- I’m sure you’ve been told not to yank the cap off a still-warm or hot car radiator. The resultant instant loss of pressure drops the boiling point of the coolant, which can then spontaneously boil violently, and come spewing out and burn ya.
Same game for the beer. The slight pressure of the carbonation lowers the freezing point. If the beer is at a temperature below it’s unpressurized freezing point but not yet at it’s pressurized freezing point, when you pop the cap the pressure is lost- and since the liquid is already colder than it’s freezing point, ice forms spontaneously.
You get the same thing with sodas as well. In the wintertime, I’ve knocked back many a canful of flavored slush.
The temperature-pressure law you are thinking of is Gay-Lussac’s law, but it only applies to gases. (Joseph Gay-Lussac was a French scientist of the early 1800’s.)
