Question

Methane gas, CH4, effuese through a barrier at a rate of 0.568 mL/minute. if an unknown gas effuese through the same barrier at a rate of 0.343 mL/minute, what is the molar mass of the gas?

a) 64.0 g/mol
b) 28.0 g/mol
c) 44.0 g/mol
d) 20.8 g/mol
e) 32.0 g/mol

Answer 1

The effusion rate of a gas is inversely proportional to the square root of its molar mass. Using this relationship, we can set up the following proportion:

(rate of CH4) / (rate of unknown gas) = sqrt(molar mass of unknown gas) / sqrt(molar mass of CH4)

Plugging in the given values and solving for the molar mass of the unknown gas, we get:

0.568 mL/min / 0.343 mL/min = sqrt(molar mass of unknown gas) / sqrt(16.04 g/mol)
1.655 = sqrt(molar mass of unknown gas) / 4.002
molar mass of unknown gas = (1.655 x 4.002^2)^2 = 32.0 g/mol

Therefore, the molar mass of the unknown gas is 32.0 g/mol. Answer: (e).