Graham's Law Calculator Formula

Understand the math behind the graham's law calculator. Each variable explained with a worked example.

Use the Graham's Law Calculator

Formulas Used

Rate₁ / Rate₂

rate_ratio = sqrt(molar_mass_2 / molar_mass_1)

Variables

VariableDescriptionDefault
molar_mass_1Molar Mass of Gas 1(g/mol)2
molar_mass_2Molar Mass of Gas 2(g/mol)32

How It Works

Graham's Law of Effusion

Formula

Rate₁ / Rate₂ = √(M₂ / M₁)

Where:

  • Rate₁, Rate₂ = effusion rates of gas 1 and gas 2
  • M₁, M₂ = molar masses of gas 1 and gas 2

    • Lighter gases effuse faster. The rate is inversely proportional to the square root of molar mass.

    Worked Example

    Compare effusion rates of H₂ (2 g/mol) and O₂ (32 g/mol).

    molar_mass_1 = 2molar_mass_2 = 32
    1. 01Rate₁/Rate₂ = √(M₂/M₁)
    2. 02Rate₁/Rate₂ = √(32/2)
    3. 03Rate₁/Rate₂ = √16
    4. 04Rate₁/Rate₂ = 4.0
    5. 05H₂ effuses 4 times faster than O₂

    Ready to run the numbers?

    Open Graham's Law Calculator