Chapter 17, Problem 99AE

Carbon monoxide is toxic because it bonds much more strongly to the iron in hemoglobin (Hgb) than does O₂. Consider the following reactions and approximate standard free energy changes:

$\begin{array}{l}\text{Hgb}+{\text{O}}_2\to {\text{HgbO}}_2\Delta G^{\circ }=-70\text{KJ}\\ \text{Hgb}+\text{CO}\to \text{HgbCO}\Delta G^{\circ }=-80\text{KJ}\end{array}$

Using these data, estimate the equilibrium constant value at 25°C for the following reaction:

${\text{HgbO}}_{\text{2}}+\text{CO}\rightleftharpoons \text{HgbCO}+{\text{O}}_{\text{2}}$