"Published in Newark, California, USA"
Two gases, HBr and CH4, have molecular weights 81 and 16, respectively. The HBr effuses through a certain small opening at the rate of 4 mL/sec. At what rate will the CH4 effuse through the same opening?
Solution:
Since the rate of flow of the gases as well as their molecular weight are involved in the problem, then we have to us the Graham's Law of Effusion and Diffusion. What is the difference between effusion and diffusion? Effusion is the process in which a gas escapes from one chamber of a vessel by passing through a very small opening or orifice while diffusion is mixing of molecules of different gases by random motion and collision until the mixture becomes homogeneous.
The rate of effusion or diffusion of a gas is inversely proportional to the square root of its density or molecular weight. The equation of Graham's Law of Effusion and Diffusion can be written as follows
From the given problem, therefore, the rate of effusion of CH4 through the small opening is
