I enjoy my beer very cold (close to freezing), and I’ve noticed a very strange phenomenon a number of times: I will place a bottle of beer in the freezer, and leave it for 30-45 minutes. Before opening the bottle, I can see that the beer is still liquid, them I will open it and pour it into the glass. Many times, the beer will be fully liquid, until it starts to foam up! At this point, it will start to freeze! I can actually see the surface begin to freeze; sometimes the entire glasswill freeze into slushy beer-ice. My question, whyn should the beer DROP in temperature? Is there cooling cused by the releade of the CO2 gas enough to shill the beer past the freezing point? Or, is the beer actually supercooled from the freezer? Any thermodynamics experts let me know!
Supercooled. I’ve seen this happen with soda left outside when the temperature dropped below freezing. It’s liquid until you pop the top, then when you release the pressure, bubbles form which create enough disturbance to cause the supercooled liquid to freeze, and you’ve got a slushy on your hands.
It may also be that when it has a high concentration of dissolved gas (CO[sub]2[/sub]), the freezing point is lower, but when the gas is removed, it freezes.
(Cite).
The Universal Gas law states:
PV=nR*T
where P=preasure, V=Volume n=amount of mol of the Gas,
R=Universal Gas Constant and T=temperature
when you uncap a beer, the gas that collects at the top of the bottle is released, and the preasure in the bottle is lowered. When you lower the preasure of a gas, you have to either increase the volume or lower the tempearture. usually, both happen.
Another factor which has to be taken into account is that a preasurised liquid has a lower freezing point.
So, when you open a beer bottle, preasure is released. This has two effects: first the escaping gas has a very low temperature (Volume increases -> preasure decreases AND temperature decreases). This lowers the temperature of the bottle and subsequently the beer. The effect is not very significant, but could make a difference in some cases. Far more important, though, is the second effect: The presure of the beer lowers the freezing point of the beer. If the beer has been cooled beyond its normal freezing point (but hasn’t frozen over due to the presure) releasing the presure will increase the freezing point. Opening the beer may cause it to freeze over.
I don’t know why it doesn’t freeze over immediately, but a WAG is that releasing the preasure takes some time (CO[sub]2[/sub] isn’t released immediately)