Question

A cylinder is filled with a mixture of an equal number of molecules of Oxygen, Carbon dioxide, and Helium. When leakage occurs, do equal amounts of gases come out? Give a reason.

Answer 1

• According to Graham's law of diffusion, the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight.

r =$\frac{1}{\sqrt{\mathrm{M}}}$.

• Since the mixture contains three gases, oxygen, carbon dioxide, and helium, the molecular masses are in the order

helium < oxygen < carbon dioxide.

• The rate of diffusion of a gas depends on its molecular mass, therefore the diffusion order is

helium >oxygen >carbon dioxide.

• Hence, from the mixture, the maximum amount of helium comes out whereas the minimum amount of carbon dioxide comes out.
• So an equal amount of gases do not come out.