Question about Temp and Ice

[cheapbeersucks]

Does anyone know for sure...

 

I pull a gatorade out of the fridge.. it's pretty cold but it's a liquid.. Once you take the cap off, from the top down it quickly becomes a frozen sludge.. Is this due to the exposure to air? Anyone know why?

[timo]

I don´t really have an answer for you but my guess would be that it´s due to the sudden change in pressure. When you open the bottle, the pressure inside the bottle suddenly changes to room pressure (I´d guess it was less before that). Maybe someone who has a phase diagram of water at hand or who has a less rusted memory of thermodynamics than me can help you more.

[5614]

Because the pressure in the bottle rapidly reduces the temperature will decrease.

[swansont]

Gatorade, though? I've seen this with carbonated beverages, but not non-carbonated ones. Unless it was supercooled, and the disturbance provided nucleation sites.

[5614]

What's Gatorade ? (other than some american drink!)

 

Spose it could be an international thing which I just aint heard of. Or maybe it's like soda which is more an American word than an English one.

 

It's not so relevant really, it's a non-carbonated drink, that's the main point.

 

swansont: I can't really think of another reason why upon opening a sealed bottle it would turn from a cold liquid to a frozen solid.

[swansont]

Gatorade is a "sports drink" - non-carbonated (not fizzy), with electrolytes in it - and it is available on your side of the pond.

[insane_alien]

supercooling seems most likely here. try this again but put a small lump of something in the gatorade bottle. if it is supercooling then after the addition of the small lump it should freeze normally as it has a "seed" to start crystalizing on. or it could be supersaturation of the electrolytes. this happens if you have a concentration of dissolved solids close to saturation and then cool it lowering the capacity of the solvent. the electrolytes start crystalizing because of the disturbances. again a small lump of something would make it crystalize out noramlly.

 

make sure the small lump is not itself soluble in the drink. don't want you poisoning yourself.

[5614]

And if it is pressure change then opening the bottle to place the "small lump" in it will make it an unfair test.

 

The 'pressure theory' would be helped by if factory-sealed bottles were pressurised. Opening it would eliminate this pressure.

 

Maybe this is a good plan, depressurise (ie. open) the bottle before putting it in the fridge and see what happens.

[timo]

My idea actually was that Gatorade is produced at room temperature and that pressure in a closed container changes when it´s cooled down, not that the bottles were under pressure when they come from the factory.

Sadly, the phase diagram of water as displayed on wikipedia does not support my idea as the phase boundary seems rather pressure-independent around 0 °C. So either the phase diagram is simply not fine enough (from the tendency as it goes to 10^8 Pa one could phantazise that the slope should be finite and falling) or the phase diagram of Gatorade does have slight differences from water or it´s simply another mechanism that causes the freezing.

[insane_alien]

no comments on supersaturation then?