Enthalpies of combustion of carbon, Hydrogen, and benzene are -94kcal/mole, - 68kcal/mole and -780kcal/mole respectively. Enthalpy of formation of benzene is

given    Cgraphite+O2g → CO2g; ΔH = −94  kcals−−(1) H2g+12O2g → H2O l; ΔH = −68  kcals−−−(2) C6H6l+152O2g → 6CO2g+3H2Ol; ΔH =  − 780 kcals−−−(3)                 Required:6Cgraphite+3H2g → C6H6l; ΔH = ? 6×eq1+3×eq2−Eq3 Δ0HfC6H6 = 6−94+3−68−−780                        =−564−204+780kJ                        =−768+780kJ=+12kJ