This exam tips covers Exam Tips: Factors Affecting Rate within Factors Affecting Rate for GCSE Chemistry. Revise Factors Affecting Rate in Rates of Reaction for GCSE Chemistry with 24 exam-style questions and 18 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 12 of 13 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
💡 Exam Tips: Factors Affecting Rate
🎯 Common Question Types:
- Explain how increasing temperature increases rate (4 marks)
- Compare two reaction graphs (3 marks)
- Explain how a catalyst works (2 marks)
- Predict the effect of doubling concentration (1-2 marks)
📝 Key Command Words:
- Explain: Give mechanism — collision frequency AND energy
- Compare: State similarities AND differences between graphs
- Suggest: Apply collision theory to new context
⚠️ Common Mistakes to Avoid:
- Saying catalysts "give energy" — they lower Ea instead
- Only mentioning one temperature effect — must mention both
- Confusing steeper gradient (faster rate) with higher plateau (more product)
Quick Check: Explain in two sentences why increasing concentration increases the rate of reaction.
Increasing concentration means there are more particles per unit volume, so the particles are closer together. This increases the frequency of collisions, leading to more successful collisions per second and therefore a faster rate.
Quick Check: Why does a catalyst not change the amount of product formed?
A catalyst only affects the rate of reaction — how quickly it reaches completion. The total amount of product depends on the moles of reactants available, not on how fast they react.
Quick Check: Which factor is the ODD ONE OUT and why — temperature, concentration, surface area, catalyst?
Catalyst is the odd one out. Temperature, concentration, and surface area all increase the frequency of collisions. A catalyst works differently — it lowers the activation energy, so a greater proportion of existing collisions are successful, without increasing collision frequency.
Practice questions for Factors Affecting Rate
Which of the following factors does NOT affect the rate of a chemical reaction?
Explain, in terms of particles, why increasing temperature increases the rate of reaction.