Dalton’s Law

In a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases. P_total= P₁+P₂+….P_n
The partial pressure of a gas is the pressure exerted by that gas on its container independent of other gases.
Since each gas in a mixture is at the same temperature & is contained in the same volume Dalton’s law states that their individual partial pressures can be simply added to find the total
pressure in a container.
P_gas1= %_{total gas1} x P_total
Example- at standard barometric pressure (760 mm Hg) oxygen is ~21% of atmospheric air.
Therefore PO₂= 0.21 x 760 mmHg = 160 mmHg