Calculate C-C bond energy from the following data:
2C + 3H2 → C2H6∆H= -84.67
C→C ∆H= 716.7
H2→2H ∆H=435.9
The energy of the C-H bond is 416 KJ / mol
Balancing the equation :
2C + 3H2 → C2H6 ..............ΔH(1)= -84.67 kJ/mol
2C(graphite) → 2C(g) ........ ΔH(2)= 716.7 x 2 kJ/mol
3H2→ 6H (g).......................ΔH(3)=435.9 x 3 kJ/mol
Adding the above equations and their enthalpies :
C2H6 → 2C(g) + 6H(g) ΔH(4)= 2828.4 kJ/mol
ΔH(4) = ΔH (C-C) +ΔH ( C-H)
ΔH (C-C) = ΔH(4) - ΔH ( C-H)
ΔH (C-C) = [2828.4-6 X 414.22] = 343.08 KJ/mol........ Answer