Soda Water

[modeste]

I have just taken a bottle of soda water out of the fridge. While it was cold it was still liquid. When I opened the bottle, it suddenly started turning to ice. I'm sure it is a simple explanation. Please help.

[ChuckFickens]

The CO2 dissolved in the soda water lowers the freezing point of the water, as long as the CO2 is kept dissolved in the water it will stay liquid.

As soon as the cap is released a large amount of the CO2 escapes, this raises the freezing point of the water so it instantly freezes (as it's already at a lower temperature than it's new freezing point)

(it happens with beer too)

[gen2]

There could be another mechanism taking effect here - Supercooling.

While left undisturbed, the soda-water may have been chilled below its freezing point. The act of opening it causes disturbance that creates nucleation points and freezing commences and progresses quite rapidly.

[modeste]

thank you both, I will check my beer next time too.

[Hymie]

I have seen this effect on bottled beer, that I have left in the freezer too long (wanting to cool it fast).

I had assumed this effect was due to the drop in pressure as a result of opening the bottle.

Water (which makes up the majority of the bottled beer) has a lower freezing point at increased pressure.

In support of my theory see the attached from Wikkipedia.

http://en.wikipedia.o...ng_curve_of_water.jpg

I trust the other poster’s can provide evidence in support of their theories.

[rojash]

According to this article:
http://www.newton.dep.../chem00/chem00543.htm

"In order to lower the freezing point of water 1 C. requires a pressure of 135 atm"

I believe soda water is normally bottled at a pressure of around 2 atm.

If that's correct then I can't see that pressure per se can play a significant role in the mechanism. Both Chuck's and gen2's answers woudl seem to be closer to the truth.

[Hymie]

Clearly my assumption is wrong; a 1ºC drop in freezing temperature will require a pressure of at least 100 atmospheres, as rojash has pointed out.

ChuckFicken’s answer is more believable to me than gen2’s, otherwise shaking the bottle unopened would cause it to freeze.

But stating that the reason is because of the release of CO2, without an explanation of the mechanism involved, does not convince me – but I don’t have a better answer.