Question

From a certain apparatus, the diffusion rate of hydrogen has an average value of 28.7 cm³ s^-1. The diffusion of another gas under the same conditions is measured to have an average rate of 7.2 cm³ s^-1 Identify the gas.

[Hint: Use Graham's law of diffusion: r₁/r₂ (M₂/M₁)^1/2, where r₁,r₂ are diffusion rates of gases 1 and 2, and M₁ and M₂ their respective molecular masses. The law is a simple consequence of kinetic theory].

Answer 1

Here,

r₁ = 28.7 cm³ s^-1

r₂ = 7.2 cm³ s^-1

m₁ = 2 g and m₂ = ?

Using the Graham's law of diffusion,

This is the molecular mass of oxygen. Therefore, the other gas is oxygen.