Graham's Law states that the rate of effusion or diffusion of a gas is inversely proportional to the square root of its molar mass. This means that lighter gases will diffuse or effuse faster than heavier gases. For example, if you compare hydrogen and oxygen, hydrogen, being lighter, will move more quickly than oxygen. The mathematical expression of Graham's Law is given by the formula: \fracRate_1Rate_2 = \sqrt\frac{Molar Mass_2Molar Mass_1} . This principle helps explain various phenomena in chemistry and is useful in applications like gas separation and understanding how gases behave in different conditions.