Thursday, March 15, 2007

A Mission!

I have just received a message from a gentleman who needs our help! It seems that a certain individual who goes by the name of Nemo has been wondering (as he is wont to do) what would happen if an extraorinarily strong container full of water were dramatically chilled. Would it freeze?

Let's assume that container is made of a material and of a construction which is sufficiently strong not to deform or burst from internal pressure. Let's further assume that the container is filled to the very top, and that the water is at a 4 deg. Therefore, any further chilling of the water from this point would result in expansion. Clearly, the water will not be able to completely tranform into regular ice. A given mass of regular ice just won't fit into a container with a volume exactly sufficient for the same mass of 4 deg C water. So what will it do? Will it form some exotic type of amorphous ice? some strange crystalline form? Perhaps Ice-9?

This article almost touches on the topic. And it's got the most amazing water phase diagram I've ever seen (see above)... but it didn't help me figure it out. I'm more confused than ever. Any thoughts?


Jokermage said...

This sounds similar but probably not the same as the super-cooled liquid effect. If you use the right container and have relatively vibration-less cooler, you can bring liquids below their freezing point and have them remain liquids.

If disturb the liquid, it will almost instantaneously freeze.

drmikey said...

Three answers strike me. 1) The contents become supercooled compressed water; or 2) it becomes highly compressed ice; or 3) containment is impossible.

Is water compressible? If not, at any outside temperature below 4 C the water cannot cool and would remain at 4 C forever with lower outside temperatures. This violates thermodynamics.

Is ice compressible enough? (Recall that the reason ice skating works is because the ice melts under the skate blade pressure down to about -20 F). To be solid normal ice the pressure would be extreme (!).

If water is significantly compressible, the ocean pressures at, say, 5 miles down, would create an interesting anomaly of density.

It is also worth checking the end point with a gedanken experiment: continue the cooling indefinitely. Liquid and solid helium act strange when cold. All solid materials above absolute zero have a vapor pressure and sublime. How does this enter here?

Based upon my beliefs about water compressibility and density of water and ice, my quick answers are 3) containment is impossible (a Catch 22); or the container contents become a new state of water.

astropixie said...

not exactly the same thing, but...

gregc (of the ORG) said...

This doesn't answer the question, but is apropos, and incredibly cool:

As to the question, my guess is compressed, cold water. drmikey suggests that if water is incompressible, then we end up with a violation of thermodynamics. I would offer that everything is compressible (just ask a neutron star or black hole). Since Nemo's question concerns "an extrorindarily strong container," I'd suggest that the water would indeed cool, and either form some variation of its typical structure (Ice-whatever, in the parlance of the article mentioned in the original post), or remain liquid.

Fun question.

Anonymous said...

The pedantic engineer in me suggests that the container is stiff, not strong. Stiffness is resistance to deformation, while strength is resistance to breakage.

Sorry, but I had to say it.

This article seems to indicate supercooling leading to a low density ice formation?