Dalton's Law of Partial Pressure

Theory

Individual component in a gas mixture exerts a pressure which is called the partial pressure (P_n) of that component. 

It can be calculated from the ideal gas law. For a multicomponent gas mixture, the partial pressure of each component can be computed as follows:

The sum of the partial pressures of the components in a gas mixture must equal the total pressure:
P_total = P_a + P_b + P_c +...
where P_total is the total pressure and P_a, P_b, P_c are the partial pressures of the components. This is known as Dalton’s law of partial pressures.
n_total = n_a + n_b + n_c + ...

Relation between mole fraction and partial pressure:

Mole fraction of a is given as .
n_total = n_a + n_b + n_c + ...