Chapter 7, Problem 7.37AP

(a)

Interpretation Introduction

Interpretation:

The dissolving of $NaCl$ is exothermic or endothermic has to be determined.

Concept Introduction:

Enthalpy $\text{H}$: it is the total amount of heat in a particular system.

The value of heat formed in a reaction $\text{ΔH}$ is calculated by the formula,

$\text{ΔH=}{{\displaystyle \sum \left(BondDissociationEnergy\right)}}_{\left(\text{reactants}\right)}-{{\displaystyle \sum \left(BondDissociationEnergy\right)}}_{\left(\text{products}\right)}$

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:

The entropy of dissolving of $NaCl$ is whether increased or decreased is to be determined.

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 $\Delta S>0$

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

(c)

Interpretation Introduction

Interpretation:

The reason for $NaCl$ readily dissolving in water has to be briefly explained.

Concept Introduction:

• Enthalpy $\left(H\right)$: It is the total amount of heat in a particular system.
• 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 $\Delta S>0$

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

• Processes having increasing in entropy are likely to be spontaneous since it is the driving force for all the natural process.
• Free energy change $\left(\Delta G\right)$: change in the free energy takes place while reactants convert to product.
• A spontaneous process takes place without the influence of any external source whereas a nonspontaneous process needs an external source to take place.