Q. Illustrate phase diagram?

Ans.

There are two things which influence phase change:

1. The pressure exerted on the surface of a substance.

2. The addition or release of heat to or from a substance.

A phase diagram illustrates how both pressure and temperature can influence a phase change. A phase diagram is essentially a pressure versus temperature graph. The specific pressure and temperature conditions for which a solid, liquid, and gas exist can be obtained from a phase diagram. The phase diagram for water is shown in the following figure:

Note: The triple point is the specific pressure and temperature where all three phases of solid, liquid, and gas are in equilibrium. The normal boiling point is the boiling point when the pressure is one atmosphere. The critical point is the point above which the gas can no longer be liquefied.