Chapter 18, Problem 18.92SP

Interpretation Introduction

(a)

Interpretation:

The definition of standard free-energy change should be determined.

Concept introduction:

The relation of total entropy is as follows:

$\Delta S_{\text{total}}=\Delta S_{\text{system}}+\Delta S_{\text{surroundings}}$

The second law of thermodynamics gives criteria for spontaneity. It states that when the sign of total entropy change is positive, the reaction is spontaneous. When the sign of $\Delta S_{\text{total}}$ is negative, the reaction is nonspontaneous. Also, all reactions are at equilibrium when total entropy change is equal to 0.

Interpretation Introduction

(b)

Interpretation:

The definition for standard free-energy of formation should be determined.

Concept introduction:

The relation of total entropy is as follows:

$\Delta S_{\text{total}}=\Delta S_{\text{system}}+\Delta S_{\text{surroundings}}$

The second law of thermodynamics gives criteria for spontaneity. It states that when the sign of total entropy change is positive, the reaction is spontaneous. When the sign of $\Delta S_{\text{total}}$ is negative, the reaction is nonspontaneous. Also, all reactions are at equilibrium when total entropy change is equal to 0.