10.6: Diffusion and Effusion

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Effusion

Exercise \(\PageIndex{1}\)

Methane gas, CH₄, effuses through a barrier at a rate of 0.961 mL/minute. If an unknown gas effuses through the same barrier at a rate of 0.343 mL/minute, what is the molar mass of the gas?

Answer

126 g/mol

\(R_{E} = \frac{1}{\sqrt{mm}}\)

\(\frac{0.961}{0.343}=\sqrt{\frac{m}{16}}\)

m = 125.5 g/mol

Exercise \(\PageIndex{2}\)

How long will it take 10.0 mL of Ne gas to effuse through a porous barrier if it has been observed that 175 minutes are required for 10.0 mL of Ar gas to effuse through the same barrier?

Answer: 124 min

Exercise \(\PageIndex{3}\)

The molar mass of an unknown gas was measured by an effusion experiment. It was found that the unknown gas effused at a rate of 9.3 × 10⁻⁶ mol/hr, whereas the nitrogen gas effused at a rate of 3.9 × 10⁻⁶ mol/hr. The molar mass of the gas is _____.

Answer: 4.9 g/mol

Exercise \(\PageIndex{4}\)

The rate of effusion of an unknown gas was measured and found to be 10.7 mL/min. Under identical conditions, the rate of effusion of pure oxygen (O₂) gas is 12.6 mL/min. Based on this information, the identity of the unknown gas could be:

a. N₂CH₂OF₂ b. CO₂N₂O c. NO d. C₂H₆ e. none of these

Answer: b. CO₂N₂O

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