Chapter 1, Problem 1.2CP

Interpretation Introduction

Interpretation: The significance of parameter a of the van der Waals equation to describe the difference in the form of the potential function of ${\text{H}}_{\text{2}}\text{O}$ and He gases needs to be explained.

Concept Introduction: The ideal gas equation is the equation that gives the relation between pressure, volume, number of moles and temperature of gases. It can be written as:

  $PV=nRT$

Here, R is Universal gas constant.

Usually, gases do not follow ideal behavior under all conditions of pressure, temperature and volumes. The relation of P, V, n and T of real gases can be given by Vander Waals equation:

  $\left(\text{P + }\frac{{\text{n}}^{\text{2}}\text{a}}{{\text{V}}^{\text{2}}}\right)\left(\text{V- n b}\right)\text{ = nRT}$

Hence,

  $\text{P = }\frac{\text{nRT}}{\text{ V-nb}}\text{ - }\frac{{\text{n}}^{\text{2}}\text{a}}{{\text{V}}^{\text{2}}}$