• The contributions made by the constituent gases towards the total pressure of a mixture of gases is called their partial pressures.

• The pressure that a constituent gas of a mixture of gases would exert if it alone occupies the volume of the container of the mixture is equal to the partial pressure of that gas.

Dalton’s law of partial pressures

In a mixture of gases which do not react with each other the total pressure is equal to the sum of the partial pressures of each of the constituent gases.

• If the partial pressures of individual gases in a mixture of gases A, B and C are PA , PB and PC respectively, total pressure of the mixture Pt = PA + PB + Pc