A liquid is in equilibrium with its vapor in a closed vessel. Which one of the following statements is necessarily true?
A)The rate of condensation is greater than the evaporation rate.
B)The rate of evaporation is greater than the condensation rate.
C)The temperature of the vapor is greater than that of the liquid.
D)Molecules of the liquid do not have enough energy to vaporize.
E)The temperature of the vapor is the same as that of the liquid.

Question

Quizplus · Accepted Answer

In equilibrium, the rates of evaporation and condensation are equal, so options A and B are not necessarily true. The temperature of the vapor and the liquid can be different, but at equilibrium, the partial pressure of the vapor is constant, which means the temperature of the vapor and the liquid are the same (option E). Option D is also not necessarily true since some molecules may have enough energy to vaporize, while others may not, leading to a balance between evaporation and condensation.

A Liquid Is in Equilibrium with Its Vapor in a Closed