Chapter 16, Problem 16.123CHP

(a)

Interpretation Introduction

Interpretation:

$\Delta H°,\Delta S°$ for the reaction given below has to be calculated

$N_{2(g)}+{\text{ 3 H}}_{2(g)}\stackrel{}{\to }{\text{ 2 NH}}_{3(g)}$

Concept Introduction:

• Standard free energy change, standard enthalpy change and standard entropy change are related as,

$\Delta G°=\Delta H°-T\Delta S°$

• $\Delta H°$ refers to standard enthalpy change.  Change in enthalpy in a reaction and heat of formation are related by the formula,

$\Delta H_{rxn}^{°}=\Sigma \Delta H_f^{°}(product)-\Sigma \Delta H_f^{°}(reac\tan t)$

Where,

$\begin{array}{l}\Delta H_{rxn}^{°}=\text{ enthalpy change in reaction}\\ \Delta H_f^{°}(product)=\text{ enthalpy or heat of formation of product}\\ \Delta H_f^{°}(reac\tan t)=\text{ enthalpy or heat of formation of }reac\tan t\end{array}$

(b)

Interpretation Introduction

Interpretation:

The sign of $\Delta S°$ for the given reaction has to be accounted.

Concept Introduction:

• Spontaneous process has positive entropy value and negative free energy, enthalpy value.
• Non-spontaneous process tends to proceed with negative entropy value and positive free energy and enthalpy.

(c)

Interpretation Introduction

Interpretation:

The spontaneity of the given reaction under $25°C$ has to be ascertained.

Concept Introduction:

• Spontaneous process has positive entropy value and negative free energy, enthalpy value.
• Non-spontaneous process tends to proceed with negative entropy value and positive free energy and enthalpy.