Chemistry A-Level
Exothermic and endothermic reactions
What Exothermic and endothermic reactions means in Chemistry A-Level, as defined for OCR.
Definition of Exothermic and endothermic reactions
Check what you remember
Read the wording for your board, then hide it and explain Exothermic and endothermic reactions in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: OCR
A reaction is exothermic when bond making releases more energy than bond breaking absorbs, and endothermic when bond breaking absorbs more energy than bond making releases.
Topics that use Exothermic and endothermic reactions
- Enthalpy changes (OCR A-Level)
Related terms
- ∆H of combustion
- ∆H of formation
- Activation energy
- Approximate estimate
- Average bond enthalpy
- Averaging over gaseous compounds
- Bond breaking and bond making
- Bond enthalpy
Using Exothermic and endothermic reactions in the exam
Check the command word and mark scheme for your exact question. After comparing your explanation with the reference, use the term in an answer on the linked topic. This practice does not predict an exam mark.
Practise Chemistry questions
Create a free account to answer exam-style questions on this topic and get feedback on your answers.
Start free
All Chemistry A-Level termsA week of Premium from your first lesson · Then the free plan continues · No card, no charge