Question

A flask contains 1/3 mole of H₂ and 2/3 mole of He. Compare the force on the wall per impact of H2 relative to that for He.

Short answer

Answer: The force exerted on the wall by He is twice than by H_2.

Step-by-step solution

Meaning of force

Pressure is defined as the force per unit area.

It means that pressure is directly proportional to the force. If the pressure is increased, more force will be exerted on the walls of the container.

Comparison between the forces on the wall per impact of H2 and He

According to Henry’s law, the partial pressure of gas in the gas mixture is directly proportional to the mole fraction of the gas.

Among the given gas mixture, the mole fraction of He is twice more than that of H₂. So, the pressure exerted by the He gas is two times greater than H₂.

Hence, the force exerted on the wall will be greater by He than by H₂.

The ratio of the impact of the gases is:

$\frac{{\mathbf{H}}_{\mathbf{2}}}{\mathbf{He}}\mathbf{=}\frac{\mathbf{1}\mathbf{/}\mathbf{3}}{\mathbf{2}\mathbf{/}\mathbf{3}}\mathbf{=}\mathbf{1}\mathbf{:}\mathbf{2}$

Therefore, the force exerted on the wall by He is twice than by H₂.