Define the following terms: (i) colligative properties (ii) molality

(i) Colligative properties

The properties of solutions which depend on the number of solute particles relative to the total number of particles present in the solution is called colligative properties, which are irrespective of nature of chemical species present.

These are:

(1) relative lowering of the vapour pressure of the solvent

(2) depression of freezing point of the solvent

(3) elevation of the boiling point of the solvent and

(4) the osmotic pressure of the solution.

(ii) Molality (m)

Molality (m) is defined as the number of moles of the solute per kilogram (kg) of the solvent.

m = molality =