Chapter 21, Problem 21.37P

Interpretation Introduction

Interpretation:

The way how the $E^{\circ }$ values are treated similarly and treated differently to ${\text{ΔH}}^{\text{o}},\Delta G^{\circ }and{S}^{\circ }$ has to be identified.

Concept Introduction:

Free energy change${\text{ΔG}}^0$: The change in the free energy takes place while reactant converts to product where both are in standard state. It depends on the equilibrium constant $\text{K}$.

  ${\text{ΔG}}^{\text{0}}\text{=}-\text{RT}\left(\text{ln}\text{K}\right)\text{=}{\text{ΔH}}^{\text{0}}-{\text{TΔS}}^{\text{0}}$

  Where $\text{T}$ is the temperature

The formula of $\text{ΔH}$ in terms of $\text{ΔG}$ and $\text{TΔS}$ is,

    ${\text{ΔH}}^{\circ }={\text{ΔG}}^{\circ }+\text{T}\Delta \text{S}$

Entropy is the measure of randomness in the system.  Standard entropy change in a reaction is the difference in entropy of the products and reactants. ${\text{(ΔS}}^{\text{°}}{}_{\text{rxn}}\text{)}$ can be calculated by the following equation.

  ${\text{ΔS}}^{\text{°}}{}_{\text{rxn}}{\text{ = S}}^{\text{°}}{}_{\text{Products}}-{\text{ S}}^{\text{°}}{}_{\text{reactants}}$

Where,

  ${\text{S}}^{\text{°}}{}_{\text{reactants}}$ is the standard entropy of the reactants

  ${\text{S}}^{\text{°}}{}_{\text{Products}}$ is the standard entropy of the products

Standard entropy change in a reaction and entropy change in the system are same.

Enthalpy is the amount energy absorbed or released in a process.

The enthalpy change in a system $\text{(Δ}{{\rm H}}_{\text{sys}}\text{)}$ can be calculated by the following equation.

  ${\text{ΔH}}_{\text{rxn}}{\text{ = ΔH}}^{\text{°}}{}_{\text{produdcts}}{\text{- ΔH}}^{\text{°}}{}_{\text{reactants}}$

Where,

  ${\text{ΔH}}^{\text{°}}{}_{\text{reactants}}$ is the standard entropy of the reactants

  ${\text{ΔH}}^{\text{°}}{}_{\text{produdcts}}$ is the standard entropy of the products

State function: A state function is thermodynamic quantity which describes equilibrium state of system and depends on the initial and final states of the system and independent of path of the system. Example: Energy.

Path function: A path function is thermodynamic quantity and its value depends on the path followed by system. Example: Heat, work