Consider the reaction for the combustion of ethanol. C 2 H 5 OH ( l ) 3 O 2 ( g ) ⟶ 3 H 2 O ( l ) 2 CO 2 ( g ) Use the enthalpies of formation given below to calculate the molar enthalpy of combustion, in kilojoules per mole, of ethanol, C 2 H 5 OH ( l ) . C 2 H 5 OH ( l ) : Δ H ∘ f = − 278 kJ/mol H 2 O ( l ) : Δ H ∘ f = − 286 kJ/mol CO 2 ( g ) : Δ H ∘ f = − 394 kJ/mol