A sample of hydrogen effuses through a porous container about 9 times faster than an unknown gas. Estimate the molar mass of the unknown gas.

164 g/mol

Explanation:

According to Graham's law, the rate of effusion of a gas (r) is inversely proportional to the square root of its molar mass (M).

rH₂/rX = √[M (X) / M (H₂) ]

(rH₂/rX) ² = M (X) / M (H₂)

M (X) = (rH₂/rX) ² * M (H₂)

M (X) = (9) ² * 2.02 g/mol

M (X) = 164 g/mol

The molar mass of the unknown gas is 164 g/mol.