Question
ΔHf C2H4 = 12.5 kcal
Heat of atomization of C = 171 kcal
Heat of atomization of H = 52.1 kcal
Bond energy C−H = 99.3 kcal .
What is C=C bond energy?
Joshi sir comment
2 heat of atomization of C + 4 heat of atomization of H - 4 bond energy of C-H - 1 bond energy of C=C = heat of formation of C2H4
2*171 + 4*52.1 - 4*99.3 - x = 12.5
solve