Chapter 9, Problem 3QRT

Interpretation Introduction

Interpretation:

The methods to measure the equilibrium vapour pressure of a liquid has to be explained.

Concept Introduction:

A liquid in an open vessel evaporates completely with the help of air and diffusion take away most of the gas phase molecules before they condense.  There is not an equilibrium between vaporization and condensation.

On the other hand, a liquid in a sealed vessel slowly evaporates as the gas phase molecules can’t escape.  When the rate of condensation equals to the rate of vaporization a dynamic equilibrium is established.  The pressure of the vapour at this equilibrium is called vapour pressure of that liquid.