Chapter 20, Problem 5QAP

Interpretation Introduction

Interpretation:

Whether the given reaction in problem 3(b) is spontaneous or not at 25° C and 1atm needs to be determined.

Concept introduction:

A spontaneous reaction can be explained as the type of reaction which proceeds automatically to give the product under available conditions.

The best parameter to obtain the spontaneous nature of a reaction is obtaining its Gibb’s free energy change as

$\begin{array}{l}\Delta G<0,\text{the reaction is spontaneous}\text{.}\\ \Delta G>0,\text{the reaction is nonspontaneous}\\ \Delta G=0,\text{the reaction is reversible(equilibrium)}\end{array}$

The Gibb’s free energy change is obtained by following formula:

$\Delta G=\Delta H-T\Delta S,\text{where H is enthalpy, T is temperature and S is entropy of the reaction}\text{.}$

Further the change in enthalpy and entropy for reactions are obtained as

$\begin{array}{l}\text{ΔH=}\sum {\text{ΔH}}_{\text{f(products)}}^{\text{0}}\text{-}\sum {\text{ΔH}}_{\text{f(reactants)}}^{\text{0}}\\ \text{ΔS=}\sum {\text{ΔS}}_{\text{298(products)}}^{\text{0}}\text{-}\sum {\text{ΔS}}_{\text{298(reactants)}}^{\text{0}}\end{array}$