Graham's Law, formulated by the Scottish chemist Thomas Graham, describes the relationship between the rates of diffusion or effusion of gases and their molar masses. It states that the rate of diffusion or effusion of a gas is inversely proportional to the square root of its molar mass.

According to Graham's Law, lighter gases diffuse or effuse more rapidly than heavier gases under the same conditions of temperature and pressure. This is because lighter gas molecules have higher average velocities and are more likely to escape or spread out in a given time compared to heavier gas molecules.

The mathematical representation of Graham's Law is expressed as:

Rate₁/Rate₂ = √(Molar Mass₂/Molar Mass₁)

Where Rate₁ and Rate₂ represent the rates of diffusion or effusion of two gases, and Molar Mass₁ and Molar Mass₂ represent their respective molar masses.

Graham's Law is particularly relevant in understanding the behavior of gases in various applications. It has practical implications in fields such as gas separation processes, gas chromatography, and understanding the movement of gases in the atmosphere. By applying Graham's Law, scientists and engineers can predict and manipulate the diffusion or effusion rates of gases, allowing for better control and optimization of processes involving gas mixtures.