Graham's Law
| Formula / Notation | r_mean ∝ √T/M; Graham's law: r₁/r₂ = √(M₂/M₁) |
|---|---|
| Also Known As | Graham's law of diffusion/effusion, effusion rate law, gaseous diffusion law |
What is Graham's Law?
Graham's law of effusion states that the rate of effusion or diffusion of a gas is inversely proportional to the square root of its molar mass. Lighter gases diffuse faster than heavier gases. This principle is used in separating isotopes and in kinetic theory of gases.
Formula & Notation
Other Names / Synonyms: Graham's law of diffusion/effusion, effusion rate law, gaseous diffusion law
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
Graham's law of effusion states that the rate of effusion or diffusion of a gas is inversely proportional to the square root of its molar mass. Lighter gases diffuse faster than heavier gases. This principle is used in separating isotopes and in kinetic theory of gases.
Graham's law is used to separate isotopes (gaseous diffusion of UF₆ for uranium enrichment, r(²³⁵UF₆)/r(²³⁸UF₆) = √(352/349) = 1.0043), to measure molar masses of gases by comparing effusion rates, and to explain the faster diffusion of lighter gases in atmospheric chemistry.
Gaseous diffusion enrichment plants (uranium isotope separation) handle UF₆, which is corrosive and reacts violently with moisture to form HF and UO₂F₂. Strict containment, radiation monitoring, and chemical safety systems are required.
The formula or notation for Graham's Law is: r_mean ∝ √T/M; Graham's law: r₁/r₂ = √(M₂/M₁)