C2 Rates and Equilibrium
Measuring rate, collision theory, concentration, pressure, surface area, temperature, catalysts and reversible equilibrium.
How to study for CCEA GCSE Double Award Science
Build each scientific explanation from a model or relationship, show quantitative working, and connect every practical claim to controlled evidence and evaluation.
Core concepts
Concept 1
Reaction rate is measured by change in reactant or product amount per unit time and can be obtained from graph gradient.
Exam cue: Identify the scientific model, relationship or practical evidence required by the command word.
Concept 2
Collision theory explains rate changes through collision frequency and the fraction with sufficient energy.
Exam cue: Describe the graph region or experimental change, then explain it using successful collision frequency rather than particles moving more.
Concept 3
At dynamic equilibrium forward and reverse reactions continue at equal rates in a closed system.
Exam cue: Use the current CCEA specification formatting and entered tier to decide whether Higher-only detail applies.
Risk pitfalls and guardrails
Saying a catalyst changes equilibrium yield or that reactions stop at dynamic equilibrium.
Guardrail: Do not import another board or science route, omit units from a calculation, or make a scientific claim beyond the stated evidence.
Giving a remembered fact without connecting it to the stated data, observation or scenario.
Guardrail: Do not import another board or science route, omit units from a calculation, or make a scientific claim beyond the stated evidence.
Importing content or paper structure from a separate-science or non-CCEA specification.
Guardrail: Do not import another board or science route, omit units from a calculation, or make a scientific claim beyond the stated evidence.
Memory anchors
Reaction rate
Change in reactant or product amount per unit time.
Activation energy
Minimum energy required for a successful collision.
Catalyst
Substance increasing rate by providing a lower-energy pathway.
Dynamic equilibrium
Equal forward and reverse rates in a closed system.
Closed system
System that does not exchange matter with its surroundings.
Graph gradient
Rate of change represented by slope.
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
How is mean reaction rate calculated from gas data?
A reaction produces 48 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.
What is Pass Harbor?
Completely free exam prep for 247 UK exams.
- Practice questions
- Flashcards
- Study guides
- Mock exams
- No registration
- No paywall
- Start instantly
“No more expensive exam prep. Quality study tools should be accessible to everyone.”