Chapter 6.6, Problem 25P

A)

Interpretation Introduction

Interpretation:

Expression for the residual molar Gibbs energy for a gas has to be determined.

Concept introduction:

Expression for the residual molar Gibbs energy for a gas is calculated using the expression for the residual molar Gibbs energy and the expression for the residual entropy.

Write the expression for the residual molar Gibbs energy $\left({\underset{\_}{G}}^R\right)$.

${\underset{\_}{G}}^R={\underset{\_}{H}}^R-T{\underset{\_}{S}}^R$

Here, residual molar enthalpy is ${\underset{\_}{H}}^R$, temperature is $T$, and residual molar entropy is ${\underset{\_}{S}}^R$

B)

Interpretation Introduction

Interpretation:

Change in Gibbs free energy of the system and process has to be determined.

Concept introduction:

Write the expression for the change in Gibbs energy.

${\underset{\_}{G}}_2-{\underset{\_}{G}}_1=\left({\underset{\_}{G}}_2-{\underset{\_}{G}}_2^{ig}\right)+\left({\underset{\_}{G}}_2^{ig}-{\underset{\_}{G}}_1^{ig}\right)-\left({\underset{\_}{G}}_1-{\underset{\_}{G}}_1^{ig}\right)$        (6)

Here, molar Gibbs energy at state 2 is ${\underset{\_}{G}}_2$, molar Gibbs energy at state 1 is ${\underset{\_}{G}}_1$, and molar Gibbs energy for an ideal gas state at state 2 and 1 is ${\underset{\_}{G}}_2^{ig},\text{and}{\underset{\_}{G}}_1^{ig}$ respectively.

First find out the Change in enthalpy and entropy of the process then find out the change in Gibbs energy of the each process individually, after that use those calculate change in the general expression for the change in Gibbs energy to obtain the change in Gibbs energy for the system.