Structural Biochemistry/Phase Equilibria

Introduction
More than one phases coexist at the same temperature and pressure.

K-Values
K-values is a phase-equilibrium ratio, for vapor-liquid systems,

$$K_i = y_i/x_i$$

$$y_i$$ is the mole fraction of a species in vapor phase, and $$x_i$$ is the mole fraction of a species in liquid phase.

For ideal solutions,

$$K_i = P_i^S/P$$

K-values can be used for calculating bubble and dew points.

Reference
Seader, J. D., and Ernest J. Henley. Separation Process Principles. Hoboken, NJ: Wiley, 2006. Print.