---
title: "Reactions That Release or Absorb Heat"
description: "Distinguish between exothermic reactions (release energy, temperature rises) and endothermic reactions (absorb energy, temperature falls), with everyday and industrial examples"
canonical: https://lightmysky.com/learn/science/reactions-that-release-or-absorb-heat-mt_UoqUPI_uNz
source: https://lightmysky.com/learn/science/reactions-that-release-or-absorb-heat-mt_UoqUPI_uNz.md
retrieved: 2026-10-19
---

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# Reactions That Release or Absorb Heat

Distinguish between exothermic reactions (release energy, temperature rises) and endothermic reactions (absorb energy, temperature falls), with everyday and industrial examples

Subject: Science · Area: Matter & Materials · Ages 12 to 13
Page: https://lightmysky.com/learn/science/reactions-that-release-or-absorb-heat-mt_UoqUPI_uNz

## Ready when they can

- Defines exothermic and endothermic in terms of energy transfer to and from the surroundings
- Gives two examples of each type from everyday life (e.g. combustion, hand warmers; photosynthesis, cold packs)
- Explains energy changes during changes of state (melting is endothermic, freezing is exothermic)
- Interprets a temperature change in an experiment to classify the reaction type

## Lesson: Reactions that heat up or cool down

Every chemical reaction moves energy between the chemicals and their surroundings. When a reaction releases energy into the surroundings, you feel the temperature rise around it. We call that an exothermic reaction. When a reaction absorbs energy from the surroundings, you feel the temperature fall. We call that an endothermic reaction. The energy doesn't vanish either way. It just moves from one place to another.

*(drawing: A lit match warms the air around it. A shaken cold pack cools your hand. Same energy idea, opposite direction.)*

**Example.** Burning wood, striking a match, and mixing wet cement are all exothermic: you can feel the heat they give off. Inside a sports cold pack, a solid dissolves in water, and that change is endothermic: it pulls heat from your hand, so the pack feels cold. Photosynthesis in a leaf is endothermic too. It takes in energy from sunlight and stores it in sugar.

Changes of state work the same way, even though no new substance forms. Melting ice absorbs energy from its surroundings, so melting is endothermic. Water freezing into ice releases energy into its surroundings, so freezing is exothermic.

**Tip.** In an experiment, your thermometer tells the story. If the temperature climbs after you mix two substances, the reaction is exothermic. If it drops, the reaction is endothermic.

**Recap.** Exothermic reactions release energy and warm things up; endothermic reactions absorb energy and cool things down.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Energy can't be created or destroyed](https://lightmysky.com/learn/science/energy-cant-be-created-or-destroyed-mt_68pIoiiG4g)
- [How Materials Change State](https://lightmysky.com/learn/science/how-materials-change-state-mt_CyV7crZ8hl)
- [Types of Chemical Reaction](https://lightmysky.com/learn/science/types-of-chemical-reaction-mt_v0K6GRi4ZL)

## Opens up

- [Reaction Profiles and Activation Energy](https://lightmysky.com/learn/science/reaction-profiles-and-activation-energy-mt_6LtFkXn_xQ)
- [Entropy and the Spread of Energy](https://lightmysky.com/learn/science/entropy-and-the-spread-of-energy-mt_a_2feH2gnE)
- [Reversible Reactions, Dynamic Equilibrium and Le Chatelier](https://lightmysky.com/learn/science/reversible-reactions-dynamic-equilibrium-and-le-chatelier-mt_Zas-V3kTiR)