Question

50 ml of each gas A and B takes 150 and 200 second respectively for effusing through a pin hole under the similar condition. if molecular mass of gas B is 36 the molecular mass of A will be?

Answer 1

rb / ra = sqrt { Ma / Mb } = Vb Ta / Tb Va

sqrt { Ma / 36 } = Va x 150 / 200 x Va

sqrt { Ma / 36 } = 15 / 20 = 3 / 4

Ma / 36 = 9 / 16

Ma = 81 / 4

Ma = 20.2

Answer 2

Answer:

The molecular mass of A will be 20.25.

Explanation:

Graham's law of diffusion:

$r\propto \frac{1}{\sqrt{\text{Molar mass}}}$

$r=\frac{v}{t}$

Molar mass of gas A = M

Molar mass of gas B = 36

Rate of diffusion of gas A =r=$\frac{50 ml}{150 s}=\frac{1}{3}ml/s$

Rate of diffusion of gas B =r'=$\frac{50 ml}{200 s}=\frac{1}{4}ml/s$

$\frac{r}{r'}=\frac{\frac{1}{3}}{\frac{1}{4}}=\sqrt{36}{M}$

Molar mass of the gas A= M = 20.25

The molecular mass of A will be 20.25.