Quote (bob08 @ Nov 6 2009 11:10pm)
Alright, I got a 6 pack of bottled sprite that I've been drinking all week. I like to freeze drinks to make a lil slushy type thing, y'kno? I froze a couple when they were maybe 1/3 full, it went like normal. Then...
Today is when I noticed this.. I put more full bottles to freeze this morning and just now, at least 12 hours later, I pull one out. It looks to be not frozen at all. Then I open it up and bam white "ice" type stuff starts forming. When I drink it, it's not ice like frozen water..but just a cool, soft, mushy type thing...
Does carbonation (and it would have to be while.. "very" carbonated, as the 1/3 full ones did what's expected) prevent or distrupt freezing? Or what is it? One substance in the drink is freezing while others aren't.. Maybe the water is freezing but others aren't?
This effect is not due to carbonation (CO2) but to pressure. Yes, the fact that CO2 is present will change the freezing temperature, but in this case this is due to temp.
This picture is called a phase diagram, and is the basic physics behind what parameters determine the phase (solid, gas, liquid) a substance is in.
As you can see, there are two parameters which affect this graph: Pressure, and Temperature.
As pressure lowers, the temperature required to make the transition between solid and liquid is also lowered, until you reach the Triple Point. This is the temperature and pressure settings at which a given substance exists as a solid, liquid, and a gas.
As a closed bottle cools, it lowers in pressure (In contrast, a closed bottle that is heated builds pressure). The moment you opened the bottle, atmospheric pressure was established. At that point, the liquid (being of the appropriate temperature to freeze at normal pressure) starts freezing.
Make sense now?
EDIT: To answer the question of why 1/3 full would freeze how you want it and why a full bottle wont is the same idea. However, when you have bottle with 1/3 the content. Only that 1/3 of the liquid is being cooled. This means that only 1/3 of the vacuum is generated, to nearly 3x the volume (because now you have more empty space in the bottle) (These are very rough numbers). This means that the effect of pressure on the system is (again, very roughly) 9 time weaker than with a full bottle.
Looking back at that phase diagram: Given the temperature of your freezer being constant... the only thing that affects the fact whether it would be frozen would be pressure. Freezing a full bottle generates more negative pressure (cause its a vacuum) than freezing a bottle 1/3 full, and thus will not freeze. See the next picture.
The Red line represents the constant temperature of your freezer.
The Green dot is the bottle that is completely full, and still in the liquid phase.
The Blue dot is the bottle that is 1/3 full, and in the solid phase.
This post was edited by unghghgh on Nov 8 2009 05:58am