A-LevelChemistryChemical energetics9701/12 · May/June 2010 · Q41 Mark

Some bond energy values are listed below. bond bond energy/kJ mol⁻¹ C-H 410 C-Cl 340 Cl-Cl 244 Br-Br 193 These bond energy values relate to the following four reactions. P Br2 → 2Br Q 2Cl → Cl2 R CH3 + Cl → CH3Cl S CH4 → CH3 + H What is the order of enthalpy changes of these reactions from most negative to most positive?

AP→Q→R→S

BQ→R→S → P

CR→Q→P→S

DS P→Q→R

✓ Correct answer

C: R→Q→P→S

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Topic: Chemical energetics, A-Level Chemistry (syllabus 9701). Multiple choice, 1 mark.
Source: A-Level Chemistry, May/June 2010 Paper 1 Variant 2, question 4.

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