Graham's Law of Effusion


Effusion is the process in which a gas escapes through a small hole. This occurs if the diameter of the hole is considerably smaller than the mean free path of the molecules. According to Graham’s law, the rate at which gases effuse (i.e., how many molecules pass through the hole per second) is dependent on their molecular weight. Graham’s law states that the rate of effusion of a gas is inversely proportional to the square root of the molar mass of its particles.

Related formulas


R1Rate of effusion of the first gas (m3/s)
R2Rate of effusion for the second gas (m3/s)
M1Molar mass of first gas (mol)
M2Molar mass of second gas (mol)