Dalton's law states that, for a mixture of gases, such as air, the toral pressure is equal to the sum of the pressures exerted by its component gases. Each pressure exerted by a component gas is known as a Partial Pressure.
The Partial Pressure of a gas g is written as P subscript g. The partial pressure of a gas in a mixture would be the same as that of the pressure of the gas if it were alone. Therefore, each gas in a mixture behaves independently of the others.
Expressing Dalton's law algebraically:
where: