Chapter 22, Problem 27A

A friend says that, in a mixture of gases in thermal equilibrium, the molecules have the same average kinetic energy. Do you agree or disagree? Defend your answer.

To determine

To explain: If the molecules in a mixture of gases at thermal equilibrium have the same average kinetic energy.

Explanation of Solution

Introduction:

A mixture of gases is said to be at thermal equilibrium when no heat flows between them. This is because all gases have the same temperature.

If the molecules in a mixture of gases are at thermal equilibrium, no heat flows between them. This also implies that no matter flows in or out of the system. Kinetic energy of all the gases therefore remains the same. For kinetic energy to be constant, lighter gases have greater speed and heavier gases have slower speed.

Conclusion:

The molecules in a mixture of gases at thermal equilibrium have the same average kinetic energy.