Chapter 18, Problem 83SCQ

(a)

Interpretation Introduction

Interpretation:

The change in value of ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{°}}$ as temperature increases for given decomposition reaction of methanol to elements should be identified.

Concept introduction:

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}$. It is related to entropy and entropy by the following expression,

${\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}{\text{=Δ}}_{\text{r}}{\text{H}}^{\text{o}}{\text{-TΔ}}_{\text{r}}{\text{S}}^{\text{o}}$

The sign of ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}$ should be positive for a product-favored reaction. Thus, spontaneous reactions are referred to those that have negative free energy formation.

(b)

Interpretation Introduction

Interpretation:

The temperature at which decomposition is product favored at equilibrium should be identified. 

Concept introduction:

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}$. It is related to entropy and entropy by the following expression,

  ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}{\text{=Δ}}_{\text{r}}{\text{H}}^{\text{o}}{\text{-TΔ}}_{\text{r}}{\text{S}}^{\text{o}}$

The sign of ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}$ should be positive for a product-favored reaction. Thus, spontaneous reactions are referred to those that have negative free energy formation.