Chapter 6, Problem 6.88P

Interpretation Introduction

Interpretation:

Determine expressions for ${\left(\frac{\partial H^{ig}}{\partial P}\right)}_V$ and ${\left(\frac{\partial H^{ig}}{\partial P}\right)}_S$ and comment why they are not zero.

Concept Introduction:

The enthalpy of an ideal gas is defined as:

  $d{H}^{ig}=C_P{}^{ig}dT$

From the above equation we can say that enthalpy is the function of temperature only for an ideal gas and independent of pressure.

The entropy change of an ideal gas is defined as:

  $d{S}^{ig}=C_P{}^{ig}\frac{dT}{T}-R\frac{dP}{P}$

Hence, entropy is function of both temperature and pressure.