What is the melting point of pure ice at normal pressure?

1 Answer
Mar 13, 2017

Answer:

0’C, or 273.15’K at 1 atm.

Explanation:

Most physical reference points are given at STP (Standard Temperature and Pressure), not NTP (Normal Temperature and Pressure). For practical applications of this sort there is not much difference, and in this case we are looking at the temperature as a function of the pressure, which is the same in both reference systems (1 atmosphere).

There is a very interesting paper here about the effects of very high pressures on the melting point of water: http://www.pnas.org/content/105/39/14779.full

When matter is transitioning from solid to liquid (melting), liquid to solid (freezing), liquid to vapor (boiling) or vapor to liquid (condensation) its temperature is fixed at the same temperature.

This is the “phase transition temperature”. This temperature will not change until all of the compound has changed phases. It is different for each different compound or element.