GCSE Chemistry: Rates of Reaction
Rates of Reaction asks you to explain why reactions speed up or slow down. Almost every question reduces to collision theory: more frequent successful collisions → faster reaction.
The factors affecting rate are temperature, concentration (or pressure for gases), surface area and catalysts. For each, you should be able to describe how it changes the rate and explain why using collision theory: more particles per unit volume → more frequent collisions; higher temperature → faster particles with more energy → more frequent and more successful collisions; greater surface area → more particles exposed → more frequent collisions; catalyst → lowers activation energy → more successful collisions per unit time.
Required practical 5 (rate using sodium thiosulfate and HCl, or magnesium and HCl) is a near-certain exam stem. You should know the method, the dependent and independent variables, controls, and how to plot and interpret the resulting graph (rate vs. concentration or rate vs. temperature).
Reading rate graphs involves calculating the rate from a tangent (initial rate = gradient at t = 0) and comparing rates between curves. Higher-tier students need to calculate rate as a quantitative gradient with units (e.g. cm³/s, g/s, mol/(dm³·s)).
Reversible reactions and dynamic equilibrium are examined as a comparison: at equilibrium, forward and backward rates are equal and concentrations are constant. Le Chatelier's principle predicts how a change in temperature, concentration or pressure shifts the equilibrium. Triple students need to apply it to the Haber process specifically.
OES generates rate questions across every factor and AI-marks each answer against the published mark scheme. The AI Study Coach can identify whether you struggle with collision theory or with graph interpretation.
What you'll learn
- The full Rates of Reaction sub-topic map and how it sits within GCSE Chemistry
- What examiners reward in Rates of Reaction questions, command word by command word
- The most common Rates of Reaction mistakes — and how to avoid them in your answers
- How to revise Rates of Reaction with notes, flashcards, exam-style questions and the AI Study Coach
- How OES generates Chemistry resources without using official copyrighted past papers
Who this is for
- Students revising Rates of Reaction as part of GCSE Chemistry
- Anyone retaking GCSE Chemistry who needs a focused review of Rates of Reaction
- Parents and tutors supporting Chemistry students on Rates of Reaction
Learning objectives
By the end of this topic you should be able to:
- Describe and explain the effect of temperature, concentration, surface area and catalysts on rate
- Use collision theory to explain rate changes
- Interpret rate graphs and calculate rate from a gradient
- Describe and apply Le Chatelier's principle to dynamic equilibrium
- (Triple) Apply Le Chatelier's principle to the Haber process
Common mistakes
- Saying 'particles move faster' without linking to more frequent successful collisions
- Forgetting to mention 'successful' collisions when explaining temperature effects
- Confusing rate and yield when applying Le Chatelier's principle
- Misreading the tangent for an initial rate calculation
- Treating dynamic equilibrium as a 'stopped' reaction
Revision tips
- Memorise the four factors and the collision-theory reason for each
- Drill rate-from-tangent calculations on five different graphs
- Use flashcards on Le Chatelier's principle (one card per change)
- Practise the required practical method as a short writing exercise
- Self-mark 6-mark essays on rate against the mark scheme
How OES helps
AI Revision Notes
Concise, spec-aligned notes for every Chemistry topic, written to match what examiners reward.
Smart Flashcards
Adaptive Chemistry flashcards that prioritise the cards you keep forgetting using spaced repetition.
Exam-Style Papers
AI-generated Chemistry practice papers in the style of real exams — not official copyrighted past papers — with mark-scheme aware feedback.
Personal AI Study Coach
A 24/7 coach that plans every Chemistry session, explains anything you ask and adapts to your weakest topics.
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- Chemistry Exam Papers
- Chemistry Practice Questions
Frequently asked questions
Is Rates of Reaction on every GCSE Chemistry specification?
Yes. Rates of Reaction is a core part of the GCSE Chemistry specification across AQA, Edexcel and OCR. Some boards weight sub-topics slightly differently, but the content on this page maps to all three.
How long should I spend revising Rates of Reaction?
Most students need 4–6 focused sessions to feel confident on Rates of Reaction: one for the notes, one or two for flashcards, and two for exam-style questions. The AI Study Coach can build a schedule for you that fits the time you have left before the exam.
Does OES use official Chemistry past papers for Rates of Reaction questions?
No. OES does not redistribute official copyrighted past papers. We generate fresh exam-style questions in the style of real AQA, Edexcel and OCR papers, marked against the published mark scheme conventions.
What are the most common mistakes on Rates of Reaction questions?
Saying 'particles move faster' without linking to more frequent successful collisions Forgetting to mention 'successful' collisions when explaining temperature effects The full list — and how to avoid each — is in the "Common mistakes" section above.
Is this topic harder for higher-tier or foundation students?
Most of Rates of Reaction is on both tiers. Higher-tier papers add a few stretch sub-topics and more demanding command words ("evaluate", "explain in detail"). The OES content is tier-aware — questions can be generated at foundation, higher or mixed difficulty.
How do I know if I've actually understood Rates of Reaction, not just memorised it?
The fastest test is to attempt a fresh exam-style question and self-mark it against the mark scheme. If you can hit every mark point in your own words, you understand it. If you keep dropping the same marks, the AI Study Coach can target those gaps directly.
Where should I go next after Rates of Reaction?
Related topics like energy changes, quantitative chemistry, organic chemistry build directly on Rates of Reaction, so they are a strong next step. You can also drill Chemistry exam-style papers to combine Rates of Reaction with everything else you have revised.
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