Rates of reaction

What you will learn

• Describe the key chemistry ideas behind rates of reaction.
• Use precise GCSE command-word language in explanations.
• Apply the idea to unfamiliar substances, data or practical contexts.
• Check answers using units, state symbols, observations or balanced equations where relevant.

Core knowledge

• Rate of reaction means how quickly reactants are used up or products are formed.
• Collision theory says particles must collide with enough energy and correct orientation to react.
• Increasing temperature increases rate because particles move faster and more collisions have enough energy.
• Increasing concentration or pressure increases rate because particles collide more often.
• Greater surface area increases rate; catalysts increase rate without being used up.

Rates of reaction and equilibrium infographic

Rates practice set

Use the worked examples and practice questions on this page as a complete study task: learn the collision theory and surface area meanings, summarise the infographic in your own words, then answer the questions using the data, equations and observations given here. Check every answer for gradient, tangent and rate calculation.

Clear explanation

Rates of reaction is built around rates of reaction and collision theory. Start by learning what collision theory and surface area mean, then connect them to the sequence in the infographic.

The key GCSE skill is to move from evidence to explanation: name the observation, data trend, particle model, structure or reaction, then explain why it supports the conclusion.

For calculation or data work, show gradient, tangent and rate calculation. For written explanations, include the specific chemistry reason rather than a memorised topic sentence.

Worked examples

Quick checks

Choose an answer, then check your thinking.

Practice questions

Practice ladder

Answers and marking guidance

The exact practice answers are hidden under each question so you can try first. Marks come from using the correct chemistry model, choosing the right equation where needed, keeping units with values, and explaining changes with precise words such as particles, ions, bonds, energy, rate, evidence and uncertainty.

Common mistakes

• Forgetting activation energy in temperature explanations.
• Using final gas volume as rate without dividing by time.
• Saying catalysts are used up.
• Reading final volume when asked for initial rate.

Extension challenge

Create a six-line revision card for rates of reaction: two definitions, one infographic detail or equation line, one equation or data check, one common mistake, and one complete explanation sentence using collision theory, surface area, catalyst.

Exam-board guidance

Short board notes only. Learn the core chemistry above first.

Next lesson

Next, continue with Rates graphs and practical graph method.