Rate of Effusion Calculator

Gas effusion is the process by which a gas escapes through a tiny opening — and lighter gases do it faster. The Rate of Effusion Calculator applies Graham's Law to compare two gases: enter the Molar Mass of Gas 1 and Molar Mass of Gas 2 (or pick from common gases using the quick-select menus) to get the Rate Ratio (r₁/r₂), which gas is faster, and the Speed Factor showing by how much.

g/mol

Enter the molar mass of the first gas

g/mol

Enter the molar mass of the second gas

Enter known rate for Gas 1 (any units)

Results

Rate Ratio (r₁/r₂)

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Faster Gas

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Speed Factor

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Effusion Rate of Gas 2

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Frequently Asked Questions

What is Graham's law of diffusion?

Graham's law states that the rate of effusion or diffusion of a gas is inversely proportional to the square root of its molar mass. Lighter gases diffuse faster than heavier gases at the same temperature and pressure.

Will a gas with higher molecular weight diffuse faster?

No, gases with higher molecular weight diffuse slower. According to Graham's law, the rate is inversely proportional to the square root of molar mass, so heavier molecules move more slowly.

Can you use Graham's law of effusion on diffusion?

Yes, Graham's law applies to both effusion (gas escaping through a small hole) and diffusion (gas spreading through another gas). The mathematical relationship is the same for both processes.

Do I need temperature or pressure for Graham's law calculations?

No, you don't need specific temperature or pressure values. Graham's law compares relative rates, and when both gases are at the same temperature and pressure, these factors cancel out in the ratio.

What units should I use for molar mass?

Use grams per mole (g/mol) for molar mass. Since Graham's law calculates ratios, the units cancel out, but consistent units are important for accurate results.

How can you use Graham's law of diffusion in real applications?

Graham's law is used in gas separation processes, uranium enrichment, determining molecular weights of unknown gases, and predicting how quickly gas leaks will spread in industrial settings.