Loading…
Loading…
GCSE Chemistry · key term
A reaction or change that transfers heat energy to the surroundings.
Used by Edexcel and OCR
Specification 7.10, 7.12, 7.16 · Paper 2
A change or chemical reaction in which heat energy is given out to the surroundings.
Revise: Exothermic ReactionsAn exothermic change or reaction is one in which heat energy is given out. The energy is transferred from the reacting chemicals to their surroundings.
Describes a change in which energy is transferred from the reacting particles to the surroundings.
Use the direction of energy transfer in your answer: an exothermic reaction gives out heat energy to the surroundings.
A temperature rise is evidence that a change is exothermic because the surroundings have received energy. Do not say that the reaction itself “gains heat”.
Do not confuse an exothermic reaction with a fast reaction: “exothermic” describes an energy change, not the reaction rate.
Create a free account to read GCSE Chemistry revision notes for your exam board and track your progress.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
A reaction direction that releases energy to the surroundings, usually as heat.
Revise: Equilibrium positionThe two directions of a reversible reaction have opposite energy changes: if the forward reaction is exothermic and releases heat, the reverse reaction is endothermic and takes in heat. Increasing temperature favours the endothermic direction, which takes in some of the added energy. Decreasing temperature favours the exothermic direction.