Freezing point water under pressure.

[Ruudvis]

I was just wondering...

What is the freezing point of water is at e.g. 2 bar?
Is there a lineair scale between pressure and temperature?

 

[prex]

Everyone should make a google search before asking so general questions.
See the phase diagram at

http://en.wikipedia.org/wiki/Water_(molecule)#Triple_point

prex

http://www.xcalcs.com

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[Ruudvis]

Thank you.

p.s. I did make a google search. English isn't my natural language, hence I didn't find the right answer.

 

[Gator]

Sometimes askers want expert opinions after looking up stuff.

 

[rmw]

Wikipedia is only as good as the last person who edited it.

rmw

 

[Cockroach]

I don't think it freezing point changes with pressure.

If you stick a tank of water outside (Northern Canada), one open to atmosphere and one under your indicated pressure, both would freeze due to thermal losses. At two bar, the temperature difference is probably neglegible. You may wish to use a chemistry book or thermodynamic reference just to be sure, and post your search results to this forum.

I do know that freezing temperature does change with fluid flow, i.e. rivers freeze much later than lakes or still bodies.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[katmar]

At 2 bar g the freezing point is -0.01234 deg C which would not be noticeable with normal instrumentation. You have to get the pressure up to 135 bar g to reduce the freezing point by 1 deg C. I doubt whether the relationship is linear.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[Compositepro]

The effect is small but real and you can see it in the curve in the wikipedia reference. The classic demonstration is that a loop of string around a block of ice that is tensioned by a hanging weight will cut through the ice. The ice under the the string melts due to pressure and then refreezes above the string where there is no pressure. Thank you Mr. Wizard.

 

[Zapster]

To add to Compositepro discussion of the classic demonstration is the explanation of the physics involved in ice-skating. Properly sharpened ice skates glide on a water film due to pressure. I remember that explanation from somewhere in school.

 

[CarlB]

I remember that explanation also. But I recently heard that was a myth, apparently the film of water is more likely due to friction melting? Anyway, here are some links if you want to explore:

http://www.physicsforums.com/archive/index.php/t-204428.html

http://en.wikipedia.org/wiki/Ice_skating