Graham's Law Gas Diffusion Calculator
Diffusion Rate Ratio
Calculate the ratio of diffusion/effusion rates of two gases from their molar masses
Find Unknown Molar Mass
Determine the molar mass of an unknown gas from its diffusion rate relative to a known gas
Common Gas Comparison
Compare diffusion rates of a gas against common reference gases
Formula
rate₁/rate₂ = √(M₂/M₁) | v_rms = √(3RT/M) | M_unknown = M_known / (rate ratio)²
Frequently Asked Questions
What is Graham's law of effusion?
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: rate₁/rate₂ = √(M₂/M₁). Lighter gases move faster and diffuse more quickly.
What is the difference between diffusion and effusion?
Effusion is the escape of gas molecules through a tiny hole into a vacuum. Diffusion is the gradual mixing of gases. Graham's law applies rigorously to effusion but provides a good approximation for diffusion as well.
How was Graham's law used historically?
Graham's law was used in the Manhattan Project to separate uranium isotopes (U-235 and U-238) as UF₆ gas. The slight mass difference (349 vs 352 g/mol) required thousands of effusion stages to achieve enrichment.
You may also need
A
Adiabatic Process Calculator
Free adiabatic process calculator. Compute final temperature, pressure, volume, and work done during an adiabatic expansion or compression of an ideal gas.
ScienceA
Isothermal Process Calculator
Free isothermal process calculator. Compute work done, heat transfer, and state changes during an isothermal expansion or compression of an ideal gas.
ScienceA
Density Calculator
Free density calculator. Calculate density, mass, or volume using the formula ρ = m/V. Includes common material densities.
Science