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What is a limiting reactant?

What is a limiting reactant?

Diagram showing a mixture of 2 H2 and 2 O2, where 2 H2 react with 1 O2 to form 2 H2O and 1 O2 remains in excess

Reactants are often not mixed in the exact ratio shown by the balanced equation. In this mixture, 2 H2 react with 1 O2 to form 2 H2O, leaving 1 O2 unreacted. The reactant that is completely used up first is the limiting reactant, because it controls the maximum amount of product that can form.

3.2.4 Limiting reactants Lesson

  1. GCSE
  2. /Chemistry
  3. /3.2.4 Limiting reactants

Step-by-step lessons on AQA GCSE Chemistry 3.2.4 Limiting reactants. Each one builds up to exam-style questions. Nail the core quantitative topics — moles, balancing equations and calculations — early on, since they underpin higher-tier questions across every paper and topic.

Lessons