Grahams Law Of Diffusion Calculator

g/mol
e.g., H₂ = 2, O₂ = 32, CO₂ = 44
g/mol
mL/s
If known, calculates rate of Gas 2.
Chemistry

Calculate the relative rates of diffusion or effusion of two gases using Graham's Law.

Formula

Rate₁/Rate₂ = √(M₂/M₁)
  • Graham's Law: lighter gas diffuses/effuses faster.
  • The ratio of rates equals the inverse square root of molar masses.
  • Temperature must be the same for both gases.

H₂ vs O₂

Inputs
  • Molar Mass of Gas 1: 2 g/mol
  • Molar Mass of Gas 2: 32 g/mol
  • Rate of Gas 1 (optional): 0 mL/s

√(32/2) = √16 = 4. H₂ diffuses 4× faster than O₂.

Frequently asked questions

What is effusion?
Effusion is the escape of gas through a tiny hole. Diffusion is the spread of gas through space.
Does Graham's Law work at any temperature?
Yes — both gases must be at the same temperature for the ratio to hold.