Pressure and Melting Ice

We all know an ice skater slides on a sliver of water because pressure on the ice causes it to melt. Now...can ice get so cold that, no matter the amount of pressure on it, it will not melt?
- jerry hoyt (age 83)
durant OK

Yes, we all learned that the pressure from the skates melts a layer of water but that's still pretty much false. the actual effect of that sort of pressure on ice scarcely lowers the melting point. Usually it's too small an effect to matter.

As for your question, yes, below about 251 K water never forms a stable liquid, regardless of the pressure. The type of ice formed does depend on the pressure. At extremely low pressures, the stable phase is a gas.

Some nice phase diagrams showing the stable forms as a function of pressure and temperature can be found here: http://www1.lsbu.ac.uk/water/water_phase_diagram.html.

Mike W.

(published on 07/06/2015)