Graham's Law Calculator
💨 Gas Laws & Fluids. Use the Graham's law formula to find rate ratio, molar mass 1, molar mass 2: pick the value you want, type the others, and the answer updates as you go.
Default: H₂ (2 g/mol) vs O₂ (32 g/mol), H₂ escapes 4× faster.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Rate ratio | no unit |
| Molar mass 1 | g/mol |
| Molar mass 2 | g/mol |
Worked example
Find the rate ratio when Molar mass 1 = 2 g/mol, Molar mass 2 = 32 g/mol.
Using Rate1/Rate2 = √(M2/M1): Rate ratio = 4.
Frequently asked questions
What is the formula for Graham's law?
Rate1/Rate2 = √(M2/M1). Default: H₂ (2 g/mol) vs O₂ (32 g/mol), H₂ escapes 4× faster.
What do the letters stand for, and what units are used?
Rate ratio, Molar mass 1 in g/mol, Molar mass 2 in g/mol.
How do you calculate rate ratio?
Put the values into Rate1/Rate2 = √(M2/M1). For example, with Molar mass 1 = 2 g/mol, Molar mass 2 = 32 g/mol, rate ratio = 4.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (rate ratio, molar mass 1, molar mass 2) and fill in the others: it rearranges the formula for you.
