Reversible Reactions

Not all chemical reactions go to completion. Some reactions can proceed in both directions — the products can react to reform the reactants. These are called reversible reactions, and they are an important part of the AQA GCSE Chemistry specification. This lesson explains what reversible reactions are, how to recognise them, and the key energy changes involved.

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What Is a Reversible Reaction?

A reversible reaction is a reaction that can proceed in both the forward and backward (reverse) directions.

In a reversible reaction:

• The forward reaction converts reactants into products
• The backward (reverse) reaction converts products back into reactants

The symbol for a reversible reaction is a double-headed arrow: A + B <=> C + D

This replaces the single arrow (-->) used for irreversible reactions.

Type of Reaction	Symbol	Description
Irreversible	-->	Reaction goes to completion; reactants fully converted to products
Reversible	<=>	Reaction can go in both directions; does not go to completion