Question

Enter your answer in the provided box. A sample of an unknown gas effuses in 14.5 min. An equal volume of H2 in the same apparatus under the same conditions effuses in 2.42 min. What is the molar mass of the unknown gas

Answer 1

Molar mass = 71.76 g/mol

Step-by-step explanation:

The relationship between molar mass and rate of effusion is given as;

Vh / Vu = √ (Mu / Mh)

The rate of effusion of a gas is inversely proportional to the square root of the mass of its particles.

Rate = volume / time (Assuming Volume = 1)

Vh = Rate of effusion of Hydrogen = 1 / 2.42

Vu = Rate of effusion of unknown gas = 1 / 14.5

Mh = Molar mass of hydrogen = 2

Mu = Molar mass of unknown gas = x

Substituting into the formular, we have;

(1 / 2.42) / (1 / 14.5) = √ ( x / 2)

5.99 = √ ( x / 2)

35.88 = x / 2

x = 71.76