Reversible Reactions and Dynamic Equilibrium
Reversibility, closed systems, dynamic equilibrium, responses to concentration, pressure and temperature, and industrial compromises.
How to study for GCSE Chemistry
Move between particle models, equations, calculations, observations and data; practise the specific required activities and paper structure named by your exam board.
Core concepts
Concept 1
At dynamic equilibrium in a closed system, forward and reverse reactions continue at equal rates, so macroscopic concentrations remain constant.
Exam cue: State the direction of the imposed change and use equation stoichiometry or energy direction to predict the response.
Concept 2
Changing concentration, pressure or temperature shifts the equilibrium position in the direction that opposes the imposed change; temperature also changes the equilibrium constant conceptually through reaction energetics.
Exam cue: Keep equilibrium position separate from how quickly equilibrium is reached.
Concept 3
Industrial conditions balance equilibrium yield with rate, energy, pressure, equipment, catalyst, raw-material and safety considerations.
Exam cue: Explain why a compromise condition is used rather than merely naming the maximum-yield condition.
Risk pitfalls and guardrails
Saying reactions stop at dynamic equilibrium.
Guardrail: Do not rely on a memorised keyword alone: preserve charges, ratios, units and conditions, and keep single Chemistry separate from Combined Science.
Claiming a catalyst increases equilibrium yield.
Guardrail: Do not rely on a memorised keyword alone: preserve charges, ratios, units and conditions, and keep single Chemistry separate from Combined Science.
Applying pressure changes to equilibria with no difference in gaseous mole numbers.
Guardrail: Do not rely on a memorised keyword alone: preserve charges, ratios, units and conditions, and keep single Chemistry separate from Combined Science.
Memory anchors
Reversible reaction
A reaction whose products can react to reform reactants.
Dynamic equilibrium
Equal forward and reverse rates in a closed system.
Concentration response
The system shifts to reduce an imposed concentration change.
Pressure response
Higher pressure favours the side with fewer moles of gas.
Industrial compromise
Balance yield and rate against energy, pressure, cost and safety.
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 symbol represents a reversible reaction?
A reversible reaction shows constant macroscopic composition. Which microscopic condition defines its 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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