Chapter 20, Problem 20.48P

(a)

Interpretation Introduction

Interpretation:

The $\Delta H_{sys}$ sign change for given reaction process should be identified.

Concept introduction:

Enthalpy change: It is defined as the amount of heat released or absorbed by the chemical reaction at constant pressure conditions.

Enthalpy$\left(H\right)$: It is the total amount of heat in a particular system.

If the value obtained for $\text{ΔH}$ in a reaction is positive then it is an endothermic reaction whereas the value obtained for $\text{ΔH}$ is negative it is an exothermic reaction.

(b)

Interpretation Introduction

Interpretation:

For the given process, the entropy $\Delta S^o$ sign has to be identified.

Concept introduction:

Entropy$\left(S\right)$: it is used to describe the disorder. It is the amount of arrangements possible in a system at a particular state.

If the disorder increases in a system, then $\Delta S>0$ positive 

If the disorder decreases in a system, then $\Delta S<0$ negative

If the disorder equal in a system, then $\Delta S=0$

(c)

Interpretation Introduction

Interpretation:

For the given process, the entropy change $\Delta S_{Surr}$ has to be identified.

Concept introduction:

Entropy $\text{S}$ : it is used to describe the disorder. It is the amount of arrangements possible in a system at a particular state. ${\text{ΔS}}_{\text{univ}}={\text{ΔS}}_{\text{sys}}+{\text{ΔS}}_{\text{surr}}$

Entropy $\text{S}$ : it is used to describe the disorder. It is the amount of arrangements possible in a system at a particular state.

Using the value for the change in enthalpy in a system and the temperature, we can calculate ${\text{ΔS}}_{surr}$

  ${\text{ΔS}}_{\text{surr}}\text{=-}\frac{{\text{ΔΗ}}_{\text{sys}}}{\text{T}}$

Where,

  $\Delta {\rm H}$ is the change in enthalpy of the system

  $\text{T}$ is the absolute value of the temperature

  $\Delta \text{S}$ is the change in entropy in the system

(d)

Interpretation Introduction

Interpretation:

For the given process, the sign of $\Delta G_{Surr}$ change with temperature has to be identified.

Concept introduction:

Free energy (or) entropy change is the term that is used to explain the total energy content in a thermodynamic system that can be converted into work.  The free energy is represented by the letter G.  All spontaneous process is associated with the decrease of free energy in the system.  The equation given below helps us to calculate the change in free energy in a system.

  $\text{ΔG = }\Delta {\rm H}\text{- T}\Delta \text{S}$

Where,

  $\text{ΔG }$ is the change in free energy of the system

  $\Delta {\rm H}$ is the change in enthalpy of the system

  $\text{T}$ is the absolute value of the temperature

  $\Delta \text{S}$ is the change in entropy in the system