Dalton’s Law of Partial Pressure

The pressure exerted by the mixtures was first studied by John Dalton in 1807. He put forward the following result known as Dalton’s Law of Partial Pressure.

“If two or more gases which don’t react chemically are enclosed in a vessel, the total pressure of the gaseous mixture is equal to the sum of the partial pressure that each gas will exert when enclosed separately in the same vessel at constant temperature.”

Let P₁, P₂ and P₃ be the pressures of three non–reacting gases A, B and C when enclosed separately in same vessel at a given temperature one by one. These pressures are called Partial Pressures. Now if all the three gases are enclosed together in same vessel at same temperature. Then, according to Dalton’s Partial Pressure Law, the total pressure exerted by mixture will be equal to sum of partial pressure.

P   =     P₁   +   P₂    +  P₃