AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
An endothermic reaction is one that takes in energy from the surroundings…
Full specification wording
Energy transfer during exothermic and endothermic reactions: An endothermic reaction is one that takes in energy from the surroundings so the temperature of the surroundings decreases.
An endothermic reaction takes in energy from the surroundings, so the surroundings cool down.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 7 of 12
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
An endothermic reaction takes in energy from the surroundings, so the surroundings cool down. Energy is transferred from the surroundings to the reacting system. In bond terms, the energy needed to break bonds in the reactants is greater than the energy released when new bonds form in the products, so the overall change absorbs energy. A practical example is the reaction of citric acid with sodium hydrogencarbonate, where the mixture temperature falls. Thermal decomposition of calcium carbonate also requires continuous heating. The observable evidence is a temperature decrease of the surroundings, measured with a thermometer or temperature sensor.
What earns the marks
- An endothermic reaction takes in energy from the surroundings.
- The temperature of the surroundings decreases during an endothermic change.
- Energy is transferred from the surroundings to the reacting system.
- Overall energy is absorbed because bond breaking takes in more energy than bond forming releases.
- A temperature drop measured with a thermometer or temperature sensor is evidence that a reaction is endothermic.
- Examples include thermal decomposition and the reaction of citric acid with sodium hydrogencarbonate.
Common mistakes and how to put them right
Saying the temperature of the reaction mixture itself decreases as the definition.
Put it right: The temperature of the surroundings decreases.
Confusing endothermic with exothermic.
Put it right: Endothermic takes in energy and cools the surroundings, while exothermic releases energy and warms them.
Thinking energy is destroyed during an endothermic change.
Put it right: Energy is transferred from the surroundings to the system.
Exam tips
- State clearly that energy is taken in from the surroundings, then describe the resulting temperature decrease.
- Use a measured temperature fall as evidence, naming the thermometer or temperature sensor used.
- When explaining in terms of bonds, compare energy taken in for bond breaking with energy released for bond forming.
Try the lesson
The start of the Energy transfer during exothermic and endothermic reactions: An endothermic reaction is one that takes in energy from the surroundings so the temperature of the surroundings decreases. lesson, made from checked teaching notes for this specification point.
Have a go first
What happens to the temperature of the surroundings during an endothermic reaction?
Listen
An endothermic reaction takes in energy from the surroundings, so the surroundings cool down. Energy is transferred from the surroundings to the reacting system. In bond terms, the energy needed to break bonds in the reactants is greater than the energy released when new bonds form in the products, so the overall change absorbs energy. A practical example is the reaction of citric acid with sodium hydrogencarbonate, where the mixture temperature falls. Thermal decomposition of calcium carbonate also requires continuous heating. The observable evidence is a temperature decrease of the surroundings, measured with a thermometer or temperature sensor. A strong answer earns marks for these points. An endothermic reaction takes in energy from the surroundings. The temperature of the surroundings decreases during an endothermic change. Energy is transferred from the surroundings to the reacting system. Overall energy is absorbed because bond breaking takes in more energy than bond forming releases. A common slip: Saying the temperature of the reaction mixture itself decreases as the definition. Instead, the temperature of the surroundings decreases. Exam tip: State clearly that energy is taken in from the surroundings, then describe the resulting temperature decrease.
See it
Key words
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Endothermic reaction
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Energy transfer from the surroundings
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Temperature decrease as evidence
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Bond breaking and bond forming energy balance
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See every definition
- Endothermic reaction
- A reaction that takes in energy from the surroundings so the temperature of the surroundings decreases.
- Energy transfer from the surroundings
- Energy is transferred from the surroundings to the reacting system during an endothermic change.
- Temperature decrease as evidence
- A temperature drop measured with a thermometer or temperature sensor is evidence that a reaction is endothermic.
- Bond breaking and bond forming energy balance
- Overall energy is absorbed because bond breaking takes in more energy than bond forming releases.
Label the diagram
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1Box 1
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3Box 3
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