Chapter 17, Problem 65A

Interpretation Introduction

Interpretation:

The fact that the vapor pressure above liquid in a closed container is in equilibrium with liquid has to be explained. The way to recognise that the system has reached a state of equilibrium has to be shown.

Concept Introduction:

Equilibrium is the exact balance between two states; one state is the opposite of the other.

Chemical equilibrium: Chemical equilibrium is a state of a chemical reaction when the rate of forward reaction is equal to the rate of backward reaction. The chemical reaction follows the law of mass action. The law of mass action states that the rate of a chemical reaction is directly proportional to the product of active masses of the reactants.

Answer to Problem 65A

The equilibrium takes place when evaporation rate becomes equal to condensation.

Explanation of Solution

The vapor pressure is developed above the liquid in the container. The molecules can transfer from the liquid phase to vapor phase. The number of gas molecules are increased they start to collide each other and some of the gas molecules condense to form a liquid. The equilibrium takes place when the rate of evaporation is equal to the rate of condensation.