The entropy of liquid mixtures: I. The theory of Raoult's Law

Raoult's law for dilute solutions is derived theoretically from a model of the liquid state by the use of statistical mechanics. This method seems to be better adapted to the problem than Planck's method. It is shown that the decrease of the molecular potential of the solvent is caused by the fact that the number of configurations of the mixture contains factors originating from the solute molecules and proportional to the number of solvent molecules. When every solute molecule contributes one such factor, the mixture obeys Raoult's law in great dilution.