Equilibrium is established between a liquid and its vapor when
A) the rate of evaporation equals the rate of condensation.
B) equal masses exist in the liquid and gas phases.
C) equal concentrations (in molarity)exist in the liquid and gas phases.
D) all the liquid has evaporated.
E) the liquid ceases to evaporate and the gas ceases to condense.

Question

Quizplus · Accepted Answer

Equilibrium is a dynamic process where the rate of the forward and reverse reactions are equal. In this case, the forward reaction is evaporation and the reverse reaction is condensation. At equilibrium, the rate of evaporation equals the rate of condensation, hence choice A is the best answer. Choices B, C, and D are incorrect because they do not involve dynamic equilibrium, and choice E is incorrect because it suggests that the system has reached a state of no change, which is not the case for equilibrium.

Equilibrium Is Established Between a Liquid and Its Vapor When