Dalton’s law of partial pressure

Aug 26, 2022, 16:45 IST

what is dalton’s law of partial pressure

The ideal gas equation pV = nRT applies to mixtures just as to pure gases. It was in fact with a gas mixture, ordinary air, that Boyle, Gay-Lussac and Charles did their early experiments. The only new concept we need in order to deal with gas mixtures is partial pressure.

The pressure exerted by a gas depends on the force exerted by each molecular collision with the walls of the container and on the number of such collisions in a unit area per unit time. If a gas contains two types of molecules, each species will engage in such collisions and thus, make a contribution to the total pressure, in exact proportion to its abundance in the mixture. The contribution that each species makes to the total pressure of gas is known as the “partial pressure” of the species. Therefore, in other words, “partial pressure of a component gas, in a gaseous mixture, is the pressure that would have been exerted, had the said component occupied the entire volume alone under identical conditions of temperature.”

The statement of Dalton’s Law is “The total pressure of a mixture of non-reacting gases is equal to the sum of their partial pressures”.