This higher tier covers Higher Tier: Interpreting Bond Energy Data within Bond Energies (HT) for GCSE Chemistry. Revise Bond Energies (HT) in Energy Changes for GCSE Chemistry with 25 exam-style questions and 15 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 7 of 15 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
🎓 Higher Tier: Interpreting Bond Energy Data
At Higher Tier, you may be asked to use bond energy data to explain why a reaction is exothermic or endothermic. You must be able to:
- Identify every bond in structural formulae (count carefully — double bonds count as one bond but have higher bond energy)
- Use coefficients — if the equation has 2CH₄, you must include bonds from both CH₄ molecules
- Compare values — a larger energy out than energy in means exothermic (ΔH negative)
- Explain trends — stronger bonds (higher bond energy) release more energy when formed; they also need more energy to break
Important note: Bond energy calculations give an AVERAGE value. Real bond energies vary slightly depending on the molecular environment, so calculated ΔH values may differ slightly from measured values.
Practice questions for Bond Energies (HT)
Which statement correctly describes the energy change when chemical bonds are broken?
Explain how you would determine, from a bond energy calculation, whether a reaction is exothermic or endothermic.