cam@aluxe.UUCP (MASCAVAGE) (01/09/86)
This morning I came across an unusual happening as I drove to work.
I could not quite understand the physics of the situation, so I look
to you scientifically oriented peoples for an explanation. Here's what
happened: I jumped in my car in the morning to go to work. It was about
21 deg.F outside. I started up, turning on the heat, and was on my way.
On the floor of the passenger side was a six-pack of sparkling water that
I had bought the day before, and left in the car overnight. About 2 or
3 min. down the road, I decided to have a drink, so I opened one of the
bottles with an opener that I had in the car. Lo and behold, a few
seconds later, the liquid in the bottle solidified (turned to cloudy ice)
from the top down. This happened within seconds, and almost all of the
liquid in the bottle had changed. The only contents of the liquid were
naturally carbonated water, and some natural flavorings(cola,cherry,
and spices). Did the gas trapped in the bottle keep it from freezing
previously? What happened? Any bright ideas ?
aluxe!camdesj@brahms.BERKELEY.EDU (David desJardins) (01/10/86)
In article <836@aluxe.UUCP> cam@aluxe.UUCP (MASCAVAGE) writes: >This morning I came across an unusual happening as I drove to work. >I could not quite understand the physics of the situation, so I look >to you scientifically oriented peoples for an explanation. Here's what >happened: I jumped in my car in the morning to go to work. It was about >21 deg.F outside. I started up, turning on the heat, and was on my way. >On the floor of the passenger side was a six-pack of sparkling water that >I had bought the day before, and left in the car overnight. About 2 or >3 min. down the road, I decided to have a drink, so I opened one of the >bottles with an opener that I had in the car. Lo and behold, a few >seconds later, the liquid in the bottle solidified (turned to cloudy ice) >from the top down. This happened within seconds, and almost all of the >liquid in the bottle had changed. The only contents of the liquid were >naturally carbonated water, and some natural flavorings(cola,cherry, >and spices). Did the gas trapped in the bottle keep it from freezing >previously? What happened? Any bright ideas ? > This is a common occurrence with very cold sodas. There are two effects at work here: 1) The main factor is that, since water expands as it freezes (and indeed at the temperature drops below 4 degrees C, as I recall), the freezing point of water at pressures above 1 atm is lowered. Your soda is already under pressure, even at room temperature; as the bottle is cooled below 4 degrees C the water starts to expand, and when it hits the freezing point and ice crystals begin to form it expands even more. Since a relatively small part of the contents of the bottle is the gas, a small increase in the volume of the water has a large effect on the pressure... So the pressure becomes high enough that the water will not freeze at 21 degrees F. But of course when the bottle is opened the pressure drops to 1 atm; the contents of the bottle are still at 21 degrees F (or lower, see (2)), and so the water freezes. Note that the act of freezing creates heat, so not all of the contents will necessarily freeze even though when you opened the bottle all of the water was below its freezing point (at 1 atm). 2) A second effect is that when a gas under pressure is allowed to expand its temperature will drop. This is how the liquid forms of gases were discovered; by compressing a quantity of the gas to a very high pressure, then releasing it. The temperature drops enough that some drops of liquid nitrogen (or whatever) can be created. In this case the expanding carbon dioxide should drop in temperature, but the pressure and quantity of gas are low enough that I don't think this would be too significant. I don't feel like actually doing the computations, but I'm sure somebody will let he know if I'm wrong... -- David desJardins
ark@alice.UucP (Andrew Koenig) (01/11/86)
Why would a bottle of soda freeze almost instantly when opened? One possibility is that when the gas was released from the bottle, it took some energy with it, reducing the temperature of the remainder. Have you ever used a CO2 cartridge to carbonate water? If you have, you'll recall that when you pick up the spent cartridge afterwards, it is extremely cold. This is the same phenomenon.
tim@ism780c.UUCP (Tim Smith) (01/15/86)
This was just discussed on net.physics. There were something like four different things that contribute to the freezing. However, I do not remeber them... -- Tim Smith sdcrdcf!ism780c!tim || ima!ism780!tim || ihnp4!cithep!tim