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In article [...] mag6@po.CWRU.Edu (Martin A. Gulaian) writes:
>
>If you stick a bottle of beer in the freezer and forget about it for
>a while, but not too long, it will be extremely cold (10 deg F?) but not
>frozen when you take it out.
>
>If you've timed it right, you can pop the top off the bottle and watch
>as the beer flash-freezes solid in a matter of a seconds. The first time
>
>I assume that the pressure in the capped beer bottle depresses the
>freezing point of beer the same way that the freezing point of water drops
>with increased pressure. When the bottle is uncapped, pressure returns to
>normal, the beer finds itself supercooled, and freezes in a hurry, starting
>at some tiny bubble maybe.
>
>My question for the net:
>
>Why does the WHOLE beer freeze solid? If the beer is only, say, 20 deg F
>below freezing, how can it absorb all the heat from the freezing ice? To
>rephrase, a beer-sized block of ice would drop a beer-sized glass
>of water a lot more than 20 deg F before melting. Shouldn't the inverse
>apply here? 
>
>Does something weird happen to the specific heat of water below its
>normal freezing point? Does beer not freeze the same way that water
>does?

	I've got a little theory for the beer problem: after being left in the
freezer for some time, even if it's cold, you've got evaporation, and the air
inside the bottle is saturated. Right after you open the bottle, the surface
of the liquid begins contact with air less humid, and thus the evaporation rate
rises enormously (also remember this air is hotter), taking a considerable 
amount of calories from the liquid and thus freezing the beer. It's analog to 
little babies at childbirth: the moment the baby is born it loses about 5000
calories (I'm not sure of the number, but it's of that sort) due to evaporation.
Did you like the theory? If you didn't, then I have another one, though this one
doesn't convince me too much:
	If I accept what you said that the beer must start its freezing at some
bubble near its surface, then this could act as a catalizer for the change in
the state. There's an experience to illustrate this: put sugar in a teaspoon,
take a lighter and try to start it aflame; it's simply impossible, it turns
into caramel (I think this isn't an english word: somebody help me with that
one) but does not inflame. Now try it again, but previously putting a little
cigarette ash with the sugar. It starts aflame quickly, because the ashes act
as a catalizer for the reaction. I don't like this theory because the analogies
are just plain abuse: combustion is a chemical reaction, while a state change
is a physical transformation.
	Please tell me your opinion about these two, OK?

>Or should I just drink my beer at refrigerator temperatures since it tastes
>better that way anyway?

	Sometimes you have to make some little sacrifices for the sake of science;)
My true opinion: drink the beer the way you like it most (the experiment is
already done, and now you can think on it with a good tasting beer at hand!)

>
>*MG

									Dagan.

mag6@po.CWRU.Edu (Martin A. Gulaian) writes:
: 
: Why does the WHOLE beer freeze solid? If the beer is only, say, 20 deg F
: below freezing, how can it absorb all the heat from the freezing ice? To
: rephrase, a beer-sized block of ice would drop a beer-sized glass
: of water a lot more than 20 deg F before melting. Shouldn't the inverse
: apply here? 

I don't think you can really call it a temperature change. It is simply
a state change - from supercooled liquid to ice - both having the same
specific heat.

Bill

In article <1h5o4nINNo2h@usenet.INS.CWRU.Edu>, mag6@po.CWRU.Edu (Martin A. Gulaian) writes:
=I assume that the pressure in the capped beer bottle depresses the
=freezing point of beer the same way that the freezing point of water drops
=with increased pressure.

That's probably part of it.

=When the bottle is uncapped, pressure returns to
=normal, the beer finds itself supercooled, and freezes in a hurry, starting
=at some tiny bubble maybe.


=My question for the net:
=
=Why does the WHOLE beer freeze solid? If the beer is only, say, 20 deg F
=below freezing, how can it absorb all the heat from the freezing ice? To
=rephrase, a beer-sized block of ice would drop a beer-sized glass
=of water a lot more than 20 deg F before melting. Shouldn't the inverse
=apply here? 

Well, when CO2 expands, it absorbs heat.  This is the basic principle used for
refrigeration systems:  Expanding a gas requires work.  The energy required to
expand the gas comes from its surroundings.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.