Chemistry · Oct / Nov 2025 · Paper 12 · Question 13

The word equations for two reactions of ethene are shown. reaction 1 ethene + hydrogen → ethane reaction 2 ethene + bromine → 1,2-dibromoethane The bond energies of the bonds involved in the reactions are shown in the table. | | bond energy in kJ / mol | |---|---| | C=C | 612 | | C–C | 347 | | C–H | 413 | | H–H | 436 | | Br–Br | 193 | | C–Br | 290 | What is the value of (ΔHreaction1 – ΔHreaction2)?

1. A+240 kJ / mol
2. B+3 kJ / mol
3. C–3 kJ / mol
4. D–246 kJ / mol

As printed in the paper