Question

The bond dissociation energy of C - H in $C{H}_4$ from the equation

C(g) + 4H(g) $⟶$ $C{H}_4$(g) $\Delta$H = -397.8 Kcal is

• A. +99.45 kcal
• B. -99.45 kcal
• C. +397.8 kcal
• D. -397.8 kcal

Answer 1

The correct option is A

+99.45 kcal

The equation for bond dissociation can be given by
$C{H}_4$(g) $⟶$ C(g) + 4H(g)$\Delta$H = 397.8 kcal
There are in total of 4 C - H bonds


Therefore the energy needed to break a C - H bond can be given by $\frac{397.8}{4}$ = + 99.45 kcal