Exothermic and endothermic reactions
What Exothermic and endothermic reactions means in Combined Science GCSE, as defined for AQA.
Definitions of Exothermic and endothermic reactions
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Reference: AQA
In an exothermic reaction energy is transferred to the surroundings, causing them to warm up, while in an endothermic reaction energy is transferred from the surroundings, causing them to cool down.
A negative overall energy change indicates an exothermic reaction, as more energy is released than absorbed, while a positive value indicates an endothermic reaction.
In an exothermic reaction the products have less energy than the reactants, while in an endothermic reaction the products have more energy than the reactants.
In an exothermic reaction, the energy released from forming new bonds is greater than the energy needed to break existing bonds.
Topics that use Exothermic and endothermic reactions
- Energy transfer during exothermic and endothermic reactions (AQA GCSE)
- Key ideas (AQA GCSE)
- The energy change of reactions (HT only) (AQA GCSE)
Related terms
- Endothermic reaction
- Energy transfer to and from the surroundings
- Exothermic reaction
- Neutralisation
- Action at a distance
- Activation energy
- Active site
- Adaptation
Using Exothermic and endothermic reactions in the exam
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