Hess’ Law together with bond energy data may be used to work out the enthalpy change of a reaction. Bromoethane, $\text{CH}_3\text{CH}_2\text{Br}$, can be prepared by reacting ethene with hydrogen bromide. $\text{CH}_2{=}\text{CH}_2 + \text{HBr} \rightarrow \text{CH}_3\text{CH}_2\text{Br}$. What is the enthalpy change for this reaction?
- A$-674\,\text{kJ mol}^{-1}$
- B$-64\,\text{kJ mol}^{-1}$
- C$+186\,\text{kJ mol}^{-1}$
- D$+346\,\text{kJ mol}^{-1}$