Chapter 18.6, Problem 18.8CYU

Interpretation Introduction

Interpretation:

The equilibrium constant for the given reaction ${\text{2H}}_{\text{2}}\text{O}\left(\text{l}\right)\rightleftarrows {\text{2H}}_{\text{2}}\left(\text{g}\right){\text{+ O}}_{\text{2}}\left(\text{g}\right)$ should be determined at ${\text{25}}^{\text{o}}\text{C}$.

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,

  ${\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}{\text{= -RTlnK}}_{\text{p}}$.

The rearranged expression is,

  ${\text{K}}_{\text{p}}{\text{= e}}^{\text{-}\frac{{\text{Δ}}_{\text{r}}{\text{G}}^{\text{o}}}{\text{RT}}}$