Dissociation enthalpies of methane, ethane and ethylene are respectively 400, 680 and 540 k cal mol^(-1) . Calculate sigmaC-H,sigma C-C and piC-C bond energies.

Dissociation enthalpies of methane, ethane and ethylene are respective

1.	Dissociation enthalpies of methane, ethane and ethylene are respectively 400, 680 and 540 k cal mol^(-1) . Calculate sigmaC-H,sigma C-C and piC-C bond energies.
Answer» Solution :Methane has four `sigma C-H` bonds. `sigma C-H` bond ENERGY `=400/4=100 "kcal "MOL"^(-1)` Ethane has six `sigma C-H` bonds AR one `sigmaC-C` bond. `sigmaC-C` bond energy `=680=(6xx100)=80k"cal mol"^(-1)`. Ethylene has for `sigmaC-H` bonds, one `sigmaC-C` bond and one `pi C-c` bond. `pi C-C` bond energy `=540-[(4xx100)+80]` `=60 "kcal mol"^(-1)`