Vapor-Liquid Equilibrium

Vapor-liquid equilibrium (VLE) occurs when a liquid and its vapor coexist in a stable balance, with the rate of molecules evaporating from the liquid equal to the rate of vapor condensing back into the liquid. This state depends on temperature, pressure, and the properties of the substances involved. At equilibrium, the amounts of liquid and vapor remain constant, though molecules continually transition between phases. VLE is fundamental in processes like distillation and refrigeration, helping us understand how different substances separate or transfer heat in industrial and natural systems.