Calculating the Molar Mass of an Unknown Gas

Thread starter irNewton
Start date Sep 21, 2009
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Gas Mass

AI Thread Summary

To calculate the molar mass of an unknown gas based on effusion times, Graham's law is applied, which states that the rate of effusion is inversely proportional to the square root of the molar mass. Given that a 10.0 mL sample of helium effuses in 5.00 minutes while the unknown gas takes 16.6 minutes, the molar mass of the unknown gas can be determined by comparing the two times. The ratio of the times indicates that the unknown gas has a higher molar mass than helium. By applying the formula derived from Graham's law, the molar mass of the unknown gas can be calculated. This method effectively utilizes the relationship between effusion time and molar mass to solve the problem.

Sep 21, 2009

irNewton

Homework Statement

It takes 16.6 min for a 10.0 mL sample of an unknown gas to effuse through a pinhole. A 10.0 -mL sample of
helium, He, required 5.00 min. What is the molar mass of the unknown gas?

Homework Equations

No idea =/

The Attempt at a Solution

No idea =/
Don't know the relationship between time and volume and moles @__@

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Sep 21, 2009

Borek

Mentor

Check Graham's law.

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