Phase Diagram Definition

What Is a Phase Diagram?

This is a phase diagram, which includes the critical point and triple point.
This is a phase diagram, which includes the critical point and triple point. Booyabazooka, Wikipedia Commons

Phase Diagram Definition

A phase diagram is a chart showing the thermodynamic conditions of a substance at different pressures and temperatures. The regions around the lines show the phase of the substance and the lines show where the phases are in equilibrium.

Parts of a Phase Diagram

Typically, a phase diagram includes lines of equilibrium or phase boundaries. On these lines, multiple phases of matter can exist at equilibrium. The lines also indicate where phase transition occur.

Triple points occur where lines of equilibrium intersect. A triple point identifies the condition at which three phases of matter can coexist.

The temperature below which a substance forms a stable solid is called the solidus. The temperature above which a substance forms a stable liquid is the liquidus.