Problem: 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:Hb + O2 → HbO2 ΔG= -70 kJ/molHb + CO → HbCO ΔG= -80 kJ/molEstimate the equilibrium constant K at 298 K for the equilibriumHbO2+CO → HbCO +O2

FREE Expert Solution

We are asked to estimate the equilibrium constant K at 298 K for the equilibrium

HbO2+CO → HbCO +O2

Calculate the overall  ΔG using Hess Law:

Hb + O2 → HbO2                ΔG1= -70 kJ/mol
Hb + CO → HbCO              ΔG2= -80 kJ/mol

Modify reactions and do the same to ΔG:

HbO2Hb  + O2                ΔG1= +70 kJ/mol    (reverse/multiply by -1)
Hb + CO → HbCO               ΔG2= -80 kJ/mol   (no change)

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HbO2+CO → HbCO +O2     ΔG= -10 kJ/mol

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Problem Details

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:

Hb + O2 → HbO2 ΔG= -70 kJ/mol
Hb + CO → HbCO ΔG= -80 kJ/mol

Estimate the equilibrium constant K at 298 K for the equilibrium

HbO2+CO → HbCO +O2