Chapter 13, Problem 84IAE

Interpretation Introduction

Interpretation:

The temperature at which the dissociation of I₂(g) become appreciable should be estimated.

Concept introduction:

For a thermodynamic equilibrium reaction, the value of Gibbs free energy, change in enthalpy and entropy can be calculated as follows:

$\begin{array}{l}{\Delta }_r{\text{H}}^0={\Delta }_f{\text{H}}^0\left(\text{products}\right)-{\Delta }_f{\text{H}}^0\left(\text{reactants}\right)\\ {\Delta }_r{\text{S}}^0={\Delta }_f{\text{S}}^0\left(\text{products}\right)-{\Delta }_f{\text{S}}^0\left(\text{reactants}\right)\\ {\Delta }_r{\text{G}}^0={\Delta }_f{\text{G}}^0\left(\text{products}\right)-{\Delta }_f{\text{G}}^0\left(\text{reactants}\right)\end{array}$

Here, ${\Delta }_r{\text{H}}^0$ and ${\Delta }_r{\text{S}}^0$ are independent of temperature but ${\Delta }_r{\text{G}}^0$ depends on temperature thus, for temperature other than the 298 K (room temperature), the value of ${\Delta }_r{\text{G}}^0$ can be calculated as follows:

${\Delta }_r{\text{G}}^0={\Delta }_r{\text{H}}^0-\text{T}{\Delta }_r{\text{S}}^0$