Ncert Exercises & Solutions

The enthalpy of atomisation for the reaction ${CH}_{4} (g) \to C (g) + 4 H (g)$ $1665 kJ {mol}^{- 1}$ . What is the bond energy of C-H bond?

In

{CH}_{4}

, there are four C-H bonds. The enthalpy of atomisation of 1 mole of

{CH}_{4}

means dissociation of four moles of C-H bond.

∴

C-H bond energy per mol

= \frac{1665 kJ}{4 mol} = 416.25 kJ {mol}^{- 1}