Chemical Potential and Phase Equilibrium (Discussion)
Channel: Physical Chemistry
Date: 2021-01-07

If the chemical potential of a substance is lower in one phase than another, then it will spontaneously undergo a phase change.

Because the chemical potential of a substance is equal in any pair of phases at equilibrium, this means it is equal in all phases that coexist -- even if they are not in direct contact with one another.

But note that the equality of chemical potential only applies across different phases, not different substances: the chemical potential of two different chemical species is generally not equal.