2.3 Rates of Reaction
Rate measurement, collision theory, concentration, pressure, surface area, temperature, catalysts, graphs and experimental design.
How to study for CCEA GCSE Chemistry
Connect particle models to observations, balance every quantitative relationship, and prepare each prescribed practical from safe method through analysis and evaluation.
Core concepts
Concept 1
Reaction rate is a change in reactant or product amount per unit time and can be measured through mass, gas volume or another suitable signal.
Exam cue: Identify what quantity changes and divide by the relevant time interval.
Concept 2
Successful collisions require enough energy and suitable contact; factors change collision frequency or the share above activation energy.
Exam cue: Explain a factor with collision frequency and successful-collision reasoning.
Concept 3
A catalyst provides a lower-activation-energy pathway and is regenerated rather than shifting the final equilibrium position.
Exam cue: Separate a steeper initial rate from the final product amount on a graph.
Risk pitfalls and guardrails
Saying particles move faster when concentration alone increases.
Guardrail: Do not import an England board, Single Award or Double Award structure, and do not replace a particle-level explanation with a vague observation.
Claiming a catalyst increases equilibrium yield.
Guardrail: Do not import an England board, Single Award or Double Award structure, and do not replace a particle-level explanation with a vague observation.
Using total completion time without considering how rate varies during the reaction.
Guardrail: Do not import an England board, Single Award or Double Award structure, and do not replace a particle-level explanation with a vague observation.
Memory anchors
Reaction rate
Change in reactant or product amount divided by time.
Collision theory
Particles react only through suitably energetic successful collisions.
Activation energy
Minimum energy required for a successful reacting collision.
Catalyst
A substance increasing rate through a lower-energy route and regenerated overall.
Initial rate
The reaction rate measured at or extrapolated to the start.
Surface-area effect
Smaller pieces expose more reacting surface and raise collision frequency.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What is reaction rate?
A reaction makes 60 cm³ gas in 30 s. What is mean rate?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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