Question

The dissociation energy of $C{H}_4$ is 400 Kcal $mo{l}^{-1}$ and that of ethane is 670 Kcal $mo{l}^{-1}$. The C - C bond energy is.

• A. 270 kcal
• B. 70 kcal
• C. 200 kcal
• D. 240 kcal

Answer 1

The correct option is B

70 kcal

$C{H}_4$ has 4 C - H bonds
$\therefore$ Energy needed to break a single C - H bond is $\frac{400}{4}$= 100 Kcal
$C_2{H}_6$ has 6 C - H bonds
$\therefore$ The C - C bond energy can be given by

​670 Kcal - 6 $\times$ 100 Kcal = 70 Kcal