2.4 Equilibrium
Reversible reactions, dynamic equilibrium, closed systems, Le Châtelier's Principle and Haber-process trade-offs.
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
Dynamic equilibrium occurs in a closed system when forward and reverse rates are equal and macroscopic amounts remain constant.
Exam cue: State whether the change favours the endothermic or exothermic direction.
Concept 2
Le Châtelier's Principle predicts how concentration, pressure and temperature changes shift an equilibrium.
Exam cue: Count gas moles on both sides before predicting a pressure effect.
Concept 3
Industrial conditions balance equilibrium yield, reaction rate, energy, pressure, safety and cost.
Exam cue: Explain why a compromise condition may be preferred to the maximum theoretical yield condition.
Risk pitfalls and guardrails
Saying reactions stop at dynamic equilibrium.
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 shifts equilibrium toward products.
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.
Applying pressure reasoning to reactions without different gas mole totals.
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
Reversible reaction
A reaction able to proceed in both forward and reverse directions.
Dynamic equilibrium
Equal forward and reverse rates in a closed system.
Le Châtelier's Principle
An equilibrium shifts to oppose an imposed condition change.
Pressure shift
Higher pressure favours the side with fewer gas molecules.
Temperature shift
Higher temperature favours the endothermic direction.
Catalyst at equilibrium
Speeds both directions without changing equilibrium composition.
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 a reversible reaction?
What is dynamic equilibrium?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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