Phase Equilibrium
The condition in which two or more phases of a substance coexist with no net transfer between them.
Formula / equation
μ_phase1 = μ_phase2
Unit
Dimensionless
In depth
Equilibrium requires the chemical potential of each component to be identical in every phase present. The Gibbs phase rule, F = C − P + 2, then determines how many variables can be altered independently while keeping all the phases in coexistence.
Examples in the real world
Ice, water and vapour coexisting only at the unique triple point, where no variable may be changed freely.