This topic summary covers Knowledge Organiser: Collision Theory & Rate of Reaction within Rates & Collision Theory for GCSE Chemistry. Revise Rates & Collision Theory in Rates of Reaction for GCSE Chemistry with 25 exam-style questions and 16 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 14 of 14 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Knowledge Organiser: Collision Theory & Rate of Reaction
Key Terms
- Rate of reaction — amount ÷ time
- Activation energy (Ea) — minimum energy for reaction
- Successful collision — energy ≥ Ea + correct orientation
- Collision theory — particles must collide with correct energy and orientation
Must-Know Facts
- Rate formula: amount ÷ time (units: g/s, cm³/s)
- Steeper graph = faster rate
- Horizontal line = reaction finished
- Same final height = same amount of product
- CEO rule: Collide + Energy + Orientation
Measuring Rate Methods
- Gas syringe — volume of gas over time
- Mass balance — mass loss over time
- Disappearing cross — turbidity timing
- Colorimeter — colour intensity change
Common Exam Errors
- Forgetting "successful collisions" in explanations
- Confusing rate with total product amount
- Missing units in rate calculations
- Not explaining WHY orientation matters
Key Equations
- Rate = amount of product formed ÷ time (or amount of reactant used ÷ time)
- Rate units: g/s, cm³/s, or mol/s
- Mean rate = gradient of tangent on concentration-time graph
Practice questions for Rates & Collision Theory
According to collision theory, which of the following must happen for a chemical reaction to take place?
Explain, using collision theory, why increasing the concentration of a reactant solution increases the rate of reaction.
Quick recall flashcards
What are the units for rate?
g/s, cm³/s, or mol/s
What is rate of reaction?
How quickly reactants are used up or products are formed