Question

Carbon monoxide (CO) is toxic because it binds more strongly to the iron in hemoglobin (Hb) than does oxygen (O2), as indicated by these approximate standard free-energy changes in blood:

reaction A:reaction B:Hb+O2Hb+CO⟶⟶HbO2,HbCO,   ΔG∘=−70 kJ/mol   ΔG∘=−80 kJ/mol

Part A

Estimate the equilibrium constant K at 298 K for the equilibrium

HbO2+CO⇌HbCO+O2

Answer 1

chage in free energy when O2 is replaced by CO = -80 - (+70) = -10 kJ/ mol

$\Delta$ G = -RT ln k

k = exp (- $\Delta$ G/ RT)

   = exp (- -10/8.314 *10^-3 * 298)

   = 56. 38