Colligative Properties and its Scope

Colligative Properties and its Scope

A solution may be considered as a homogeneous (single phase) mixture of two or more substances. It is said to be `binary' if two substances are present and `ternary' if three substances are present and `quaternary' if four substances are being present etc. In a binary solution, the component present in larger amount is called as solvent and the component in smaller amounts is called as solute. Solvent and solute together make a solution. In dilute solutions, very small amount of the solute is present.

A colligative property of a solution depends purely on the number of particles dissolved in it, rather than on the chemical nature of the particles. The colligative properties can be regarded as the properties of the solvent in a given solution. Generally, the solute is considered as non-volatile. The various colligative properties are as below :

1.     Lowering of vapour pressure of th solvent (∆p)

2.     Elevation of boiling point of the solvent (∆T_b)

3.     Depression of freezing point of the solvent (∆T_f)

4.     Osmotic Pressure(Pi)

The important scope of the measurement of colligative properties lies on its use to determine the molar mass of the non-volatile solute dissolved in the dilute solution.