The heat of formation of ethane is `-19.46 kcal`. Bond enegries of `H-H, C -H` and `C- C` bonds are `104.18, 99.0` and `80.0 kcal`, respectively. Calculate the heat of atomisation of graphite.

The Bond energy of C=C, C-C, C-H and H-H are 147, 83, 99 and 104 kcal/mol respectively then calculate heat of hydrogen of ethene.

The heat of combustion of ethyl alcohol is -300 kcal. If the heats of formation of CO_(2)(g) and H_(2)O(l) are -9.3 and -68.5 kcal respectively, calculate the heat of formation of ehtyl alcohol.

Calculate the resonance enegry of isoprene (C_(5)H_(8)) from the data given. Standard Heats of combustion of isoprene, carbon and hydrogen are -3186, -393.5 , and -285.83 kJ mol^(-1) , respectively. Bond energies of C=C, C-C, C-H and H-H bonds are 615, 348, 413 and 435.8 kJ mol^(-1) respectively. Standard heat of sulbilmation of graphite is 718.3 kJ mol^(-1) .

Heat of formation of 2 mol of NH_(3)(g) is =90 kJ , bond energies of H-H and N-H bonds are 435kJ and 390 kJ mol^(-1) , respectively. The value of the bond enegry of N-=N will be