Question

Describe what is meant by dynamic equilibrium in terms of the vapor pressure of a liquid.

Short answer

Equilibrium: There is no change in composition; the vapor pressure is constant.

Dynamic: Two processes at which vapor to liquid and liquid to vapor both occur, but they both have equal rates, so the composition of the vapor present is constant.

When a liquid is in dynamic equilibrium, the rates at which evaporation is taking place and the rate at condensation is taking place are equal to each other. These processes never cease. Hence, it is known as dynamic.

Step-by-step solution

Vapor pressure

The vapor pressure of a liquid is the pressure exhibited by the liquid when it is in equilibrium with its vapor in a closed vessel.

Equilibrium

Two processes at which vapor to liquid and liquid to vapor both occur, but they both have equal rates, so the composition of the vapor present is constant.

When a liquid is in dynamic equilibrium, the rates at which evaporation is taking place and the rate at condensation is taking place are equal to each other. These processes never cease. Hence, it is known as dynamic.