A-LevelChemistryChemical energetics9701/12 · Feb/Mar 2018 · Q91 Mark

Hess' Law and bond energy data can be used to calculate the enthalpy change of a reaction. Bromoethane, CH₃CH₂Br, can be made by reacting ethene with hydrogen bromide. CH₂=CH₂ + HBr → CH₃CH₂Br What is the enthalpy change for this reaction?

A–674 kJ mol⁻¹

B–64 kJ mol⁻¹

C+186 kJ mol⁻¹

D+346 kJ mol⁻¹

✓ Correct answer

B: –64 kJ mol⁻¹

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Topic: Chemical energetics, A-Level Chemistry (syllabus 9701). Multiple choice, 1 mark.
Source: A-Level Chemistry, Feb/Mar 2018 Paper 1 Variant 2, question 9.

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