Freezing Point of Solutions

the temperature at which the crystallization of a solid phase from a solution commences. The freezing point of solutions is lower than the freezing point of the pure solvent since the partial vapor pressure over the solution is always lower than the vapor pressure over the solvent itself at the same temperature. Eutectics have invariable freezing points. The relationship between the freezing point and composition of a solution is defined by Raoult’s laws. The relationship can be represented graphically by a phase diagram; it is investigated, in particular, in binary systems. The study of the lowering of the freezing point of solutions constitutes the subject matter of cryoscopy.