Endothermic Reactions

In this lesson you will learn about endothermic reactions — reactions that absorb energy from the surroundings. You will explore examples, learn how to draw and interpret reaction profile diagrams for endothermic processes, compare endothermic and exothermic reactions side by side, and study a practical investigation that demonstrates an endothermic change. This topic is part of the Edexcel GCSE Chemistry (1CH0) specification.

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What Is an Endothermic Reaction?

An endothermic reaction is a chemical reaction that takes in (absorbs) energy from the surroundings. The surroundings get cooler and there is a measurable temperature decrease.

In an endothermic reaction:

• The energy needed to break bonds in the reactants is greater than the energy released by forming new bonds in the products.
• The shortfall in energy is taken from the surroundings, usually as heat (thermal energy).
• The products have more energy than the reactants.
• The overall energy change (ΔH) is positive.

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Examples of Endothermic Reactions