Freezing point depression (cryoscopy)


Colligative properties are properties of solutions that depend upon the ratio of the number of solute particles to the number of solvent molecules in a solution, and not on the type of chemical species present. This number ratio can be related to the various units for concentration of solutions. Colligative properties result because of the dissolution of nonvolatile solute in a volatile liquid solvent. They are independent of the nature of the solute particles, and are due essentially to the dilution of the solvent by the solute. Freezing-point depression is a colligative property. Freezing-point depression describes the process in which adding a solute to a solvent decreases the freezing point of the solvent. The freezing point of a pure solvent is lowered by the addition of a solute which is insoluble in the solid solvent, and the measurement of this difference is called cryoscopy.

Related formulas


ΔTfFreezing point depression (K)
ivan 't Hoff factor (dimensionless)
KfCryoscopic constant, (1.86°C kg/mol for the freezing point of water) (K*kg/mol)
mmolality (mol/kg)