Textbook Problem

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

     $\begin{array}{c}\text{Hb}\text{+}{\text{O}}_2\to {\text{HbO}}_2\Delta G°=-70\text{kJ}\\ \text{Hb}\text{+}\text{CO}\to \text{HbCO}\Delta G°=-80\text{kJ}\end{array}$

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

     ${\text{HbO}}_2+\text{CO}\rightleftharpoons \text{HbCO}\text{+}{\text{O}}_2$