From the heats of formation tables the following values are obtained:

DH^o (O₂) = 0 kcal/mole (gaseous diatomic form of oxygen at 25 ^oC)

DH^o (n-C₄H₁₀) = -30.0 kcal/mole (gaseous n-butane at 25 ^oC; b.p. -0.5 ^oC)

DH^o (CO₂) = -94.05 kcal/mole (gaseous CO₂ at 25 ^oC)

DH^o (H₂O) = -57.8 kcal/mole (gaseous H₂O at 25 ^oC)

Using the formula:

DH^o_(rxn) = DH^o _(combustion) = DH^o _(products) - DH^o_(reactants)

we have for,

DH^o_(rxn) = DH^o _(combustion) = [8 (-94.05) + 10 (-57.8)] - [2 (-30.0) + 13 (0)]

DH^o_(rxn) = DH^o _(combustion) = [ (-752.40) + (-578.0) - (-60.0) + (0)]

DH^o_(rxn) = DH^o _(combustion) = [(-1330.4) - (-60.0) = -1270.4 kcal/mole

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