This introduction covers The Currency of Chemical Reactions 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 1 of 15 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.
📖 The Currency of Chemical Reactions
Bond energy is like a bank balance for the reaction! Breaking bonds = the reaction withdraws money (energy must be put IN). Making bonds = the reaction deposits money (energy is given OUT). If the reaction earns more than it spends — more energy released making bonds than was needed to break them — the reaction is exothermic overall. If it spends more than it earns, it is endothermic. Note: always count from the reaction's perspective. Breaking bonds costs the reaction energy (energy flows in from the surroundings); making bonds pays the reaction energy (energy flows out to the surroundings).
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.