Graham's Law Calculator

Calculate the rate of effusion or diffusion of gases using Graham's Law. Compare rates based on molar masses and solve for unknown values.

g/mol

Enter molar mass in grams per mole

g/mol

Enter molar mass in grams per mole

relative units

Leave blank to calculate, or enter known rate

relative units

Reference rate (default = 1)

Results

Rate Ratio (A/B)

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Rate of Gas A

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Mass Ratio (B/A)

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Speed Factor

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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, diffusion rate is inversely related to the square root of molar mass, so lighter gases always diffuse faster.

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

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

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

No, temperature and pressure are not needed when comparing rates of two gases. Graham's law gives the ratio of rates, and T and P cancel out when both gases are at the same conditions.

What units should I use for molar mass?

Use grams per mole (g/mol) for molar mass. Since Graham's law calculates ratios, the specific units don't matter as long as both gases use the same units consistently.

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

Graham's law is used in gas separation processes, uranium enrichment, gas leak detection, and understanding how different gases spread in the atmosphere. It's also important in respiratory physiology and industrial gas processing.

What's the difference between diffusion and effusion?

Diffusion is when gas molecules spread out and mix with other gases in open space. Effusion is when gas escapes through a small opening or pore. Graham's law applies to both processes with the same mathematical relationship.

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