ChemBench

Graham's Law Calculator

Lighter gases escape faster.

Rate is inversely tied to the square root of mass

Graham's Law says a gas's effusion rate is inversely proportional to the square root of its molar mass — lighter molecules move faster on average and escape through a small opening more quickly.

Real application: isotope separation

This exact principle was used historically to separate uranium-235 from uranium-238 via gaseous diffusion, exploiting the tiny mass difference between isotopes of the same element.

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ChemBench

Graham's Law Calculator

Lighter gases escape faster.

Molar mass of gas 1 (g/mol)

Molar mass of gas 2 (g/mol)

Rate ratio (1:2)

Rate₁/Rate₂ = √(M₂/M₁)

What you entered

Molar mass of gas 1 (g/mol): 2Molar mass of gas 2 (g/mol): 32

1
Rate₁ ÷ Rate₂ = √(M₂ ÷ M₁)
√(32 ÷ 2)= 4

Result

Rate ratio (1:2): 4

Gas 1 effuses 4× faster than gas 2.

Rate is inversely tied to the square root of mass

Graham's Law says a gas's effusion rate is inversely proportional to the square root of its molar mass — lighter molecules move faster on average and escape through a small opening more quickly.

Real application: isotope separation

This exact principle was used historically to separate uranium-235 from uranium-238 via gaseous diffusion, exploiting the tiny mass difference between isotopes of the same element.