What Happens to Water Molecules When They Can't Expand?

[RickVS]

I've always been curious about the following:

What would happen to water on a molecular level if water were frozen but was unable to expand? Would it just not freeze? Or would the molecules lose their physical properties, particularly in relation to one another?

And what would happen to water on a molecular level if water were boiled but was unable to expand? Would it just not turn into a gas? What if you heated it to almost the melting point of its steel container? And again, how would this effect its molecular structure?

I'm thinking if you had a gallon of water in the middle of a steel or lead block the size of a city block (preventing the water from cracking or bursting its container, and then cooled or heated it accordingly. There would be no place for the water to expand. Thanks!

Rick

 

[Nemus]

There are several high pressure ice forms. The crystal structures are somewhat different than the normal diamond like ice. Some of the high pressure ice forms are expected to exist in e.g. the icy moons of jupiter.
If you heat water in a sealed container it just gets hotter (and very reactive). It takes quite some pressure to keep it from expanding. More interesting is supercritical water but that takes us off track...

 

[Borek]

http://www.btinternet.com/~martin.chaplin/phase.html

It will froze as Ice VI at about 600 MPa (6000 atm).