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Moderate

Graham's Law and the KMT

APCHEM-8MWCYY

Effusion is the process of a gas escaping into an empty container (in other words, a vacuum). Graham's law of effusion relates the relative rates of effusion for two gases to their molar masses. The rate at which a gas effuses is a measure of the root mean square velocity of the molecules.

If the average velocity of methane molecules, $C{H}_{4}$, is $5.00\times { 10 }^{ 4 } \text{ cm/s} $ at a particular temperature and pressure, what is the average velocity of helium atoms at the same temperature and pressure?

A

$2.50\times{10}^{4}\text{ cm/s} $

B

$5.00\times { 10 }^{ 4 }\text{ cm/s} $

C

$1.25\times { 10 }^{ 4 }\text{ cm/s} $

D

$1.00\times { 10 }^{ 5 }\text{ cm/s} $