Problem: Three common hydrocarbons that contain four carbons are listed here, along with their standard enthalpies of formation:HydrocarbonFormulaHf(kJ/mol)1,3-ButadieneC4 H6 (g)111.91-ButeneC4 H8 (g)1.2n-ButaneC4 H10 (g)-124.7For 1,3-Butadien calculate the molar enthalpy of combustion to CO2 (g) and H2 O(l).

We are asked to calculate the molar enthalpy of combustion to CO₂ (g) and H₂O(l) for 1,3-Butadiene.

$\boxed{\mathbf{\Delta H}{\mathbf{°}}_{\mathbf{rxn}}\mathbf{=}\mathbf{\Delta H}{\mathbf{°}}_{\mathbf{f}\mathbf{,}\mathbf{ }\mathbf{prod}}\mathbf{-}\mathbf{\Delta H}{\mathbf{°}}_{\mathbf{f}\mathbf{,}\mathbf{ }\mathbf{react}}}$

Note that we need to multiply each ΔH˚_f by the stoichiometric coefficient since ΔH˚_f is in kJ/mol. 

Also, note that ΔH˚_f for elements in their standard state is 0.

Balanced reaction: 

C₄H_6(g) + 11/2 O_2(g)→ 4 CO_2(g) + 3 H₂O_(g)