Cambridge IGCSE·Co-ordinated Sciences 0654·Chemistry
Chemical Energetics
Key knowledge — Chemical Energetics
Formulas & equations
q = mcΔT (energy = mass × specific heat capacity × temperature change)ΔH = energy of bonds broken − energy of bonds formed (endothermic if positive)
Key facts & rules
- Exothermic reaction: releases energy to surroundings → temperature rises. Products have less energy than reactants.
- Endothermic reaction: absorbs energy from surroundings → temperature falls. Products have more energy than reactants.
- Activation energy: minimum energy needed for a reaction to occur.
- Catalyst: lowers activation energy → increases reaction rate without being consumed.
- Bond breaking: endothermic (energy input needed). Bond forming: exothermic (energy released).
- If bonds broken > bonds formed (energy): overall endothermic.
- Energy level diagram: reactants → transition state (Ea peak) → products.
IGCSE Chemistry — Chemical energetics
786 Cambridge IGCSE 0654 chemistry past paper questions on chemical energetics, organised by subtopic. Pick a subtopic to start practising.
About chemical energetics on IGCSE 0654
Exothermic and endothermic reactions, energy level diagrams, and bond making and breaking.