CAIE A Level Chemistry 9701 · Group 17
The bond energies of the hydrogen–halogen bonds are: H–F 562 kJ mol⁻¹, H–Cl 431 kJ mol⁻¹, H–Br 366 kJ mol⁻¹, H–I 299 kJ mol⁻¹.
Compare the thermal stabilities of the hydrogen halides and explain the trend in terms of bond strengths.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.