Question

How do changes of state establish equilibrium?

Answer 1

Changes of state reach equilibrium when the rates of the forward and reverse processes occur at the same rates.

For example, when a container is partially filled with liquid water, some of the water will evaporate to the gas phase. When the concentration of water vapor is high enough that the rate of condensation is equal to the rate of evaporation, the system is said to have achieved its equilibrium vapor pressure.