Given: Heat of combustion of carbon and carbon monoxide are −393.5and−283.5kJmol−1, respectively.
(i) C+O2→CO2;ΔH1=−393.5kJmol−1
(ii) CO+21O2→CO2;ΔH2=−283.5kJmol−1
To find the heat of formation of CO per mole.
C+21O2→CO
ΔHf of CO
From equations (i) and (ii),
=−393.5−(−283.5)
=−110 kJmol−1