Using the average bond energies in the table

CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics

Problem

Using the average bond energies in the table, calculate the approximate enthalpy change,

\Delta H

, for the reaction below.

\text{CH}_{4}(g)+\text{Cl}_{2}(g)\rightarrow \text{CH}_{3}\text{Cl}(g)+\text{HCl}(g)

Bond energies (

\text{kJ}\,\text{mol}^{-1}

\text{C–H}\,=\,413 \quad \text{C–Cl}\,=\,328 \quad \text{H–Cl}\,=\,431 \quad \text{Cl–Cl}\,=\,243

Which of the following is closest to the predicted

\Delta H

for the reaction? (a)

+103\,\text{kJ}\,\text{mol}^{-1}

(b)

+328\,\text{kJ}\,\text{mol}^{-1}

(c)

-103\,\text{kJ}\,\text{mol}^{-1}

(d)

-346\,\text{kJ}\,\text{mol}^{-1}