Chapter 18, Problem 78SCQ

Interpretation Introduction

Interpretation:

The equilibrium vapor pressure of iodine at $\text{25 }°\text{C}$ should be calculated using ${\text{Δ}}_{\text{f}}{\text{G}}^{\text{o}}$.

Concept introduction:

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}$. It can be calculated in a similar manner as entropy and enthalpy. The expression for the free energy change is:

  ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{°}}\text{= }\sum {\text{nΔ}}_{\text{f}}{\text{G}}^{\text{°}}\left(\text{products}\right)\text{- }\sum {\text{nΔ}}_{\text{f}}{\text{G}}^{\text{°}}\left(\text{reactants}\right)$

${\text{ΔG}}^{\text{o}}$ is related to the equilibrium constant $\text{K}$ by the equation, ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}{\text{= - RT lnK}}_{\text{p}}$