Chapter 3, Problem 3E.1P

(a)

Interpretation Introduction

Interpretation: The given expression has to be derived.

Concept introduction: To calculate the changes in Gibbs-energy with respect to temperature, the Gibbs-Helmholtz equation is used.  The Gibbs-Helmholtz equation is expressed as,

    ${\left(\frac{\partial \left(\frac{G}{T}\right)}{\partial T}\right)}_p=-\frac{H}{T^2}$

Where,

• $G$ is the Gibbs-free energy.
• $T$ is the temperature.
• $H$ is the enthalpy.

(b)

Interpretation Introduction

Interpretation: The value of ${\Delta }_{\text{r}}G°$ and ${\Delta }_{\text{r}}H°$ has to be calculated for the given reaction at a given temperature.

Concept introduction: Enthalpy is the internal heat content of the system.  Under constant pressure, a system can do expansion work under the effect of energy supplied as heat known as enthalpy change of the system.  Therefore, the measure of amount of heat supplied to the system gives the enthalpy change of the system.  The change in Gibbs free energy for a reaction when reactants and products are present in their standard states of pressure, forms and concentration is represented by ${\Delta }_{\text{r}}{G}^{\text{ο}}$.

(c)

Interpretation Introduction

Interpretation: The value of ${\Delta }_{\text{r}}G°$ at $375\text{K}$ has to be calculated.

Concept introduction: To calculate the changes in Gibbs-energy with respect to temperature, the Gibbs-Helmholtz equation is used.  The Gibbs-Helmholtz equation is expressed as,

    ${\left(\frac{\partial \left(\frac{G}{T}\right)}{\partial T}\right)}_p=-\frac{H}{T^2}$

Where,

• $G$ is the Gibbs-free energy.
• $T$ is the temperature.
• $H$ is the enthalpy.