Graham's Law Calculator (Effusion Rate)
Graham's law calculator: relative effusion or diffusion rates of two gases from their molar masses, or an unknown molar mass.
r1r2 = √M2M1
How to use this calculator
- Choose the quantity you want under “Solve for”.
- Type the known values and pick their units: any combination works.
- The result updates as you type. Open “Show the steps” to see the substitution.
Lighter gases escape faster: r₁/r₂ = √(M₂/M₁).
Formula
r1r2 = √M2M1
| Symbol | Quantity | Units |
|---|---|---|
| M1 | Molar mass of gas 1 | g/mol, kg/mol |
| M2 | Molar mass of gas 2 | g/mol, kg/mol |
| r1/r2 | Rate ratio r₁/r₂ | — |
Worked example
Given: M1 = 2.016 g/mol · M2 = 32 g/mol
r1/r2 = √(M2/M1)
Result: r1/r2 = 3.9841
Frequently asked questions
How much faster does H₂ effuse than O₂?
About 3.98 times faster.