This topic summary covers Knowledge Organiser: Dynamic Equilibrium & Le Chatelier's Principle within Equilibrium (HT) for GCSE Chemistry. Revise Equilibrium (HT) in Rates of Reaction for GCSE Chemistry with 23 exam-style questions and 18 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. 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: Dynamic Equilibrium & Le Chatelier's Principle
Key Terms
- Dynamic equilibrium — forward rate = backward rate
- Closed system — required for equilibrium
- Le Chatelier's Principle — system opposes change
- Equilibrium position — left (reactants) or right (products)
Le Chatelier Quick Rules
- Temp ↑ → endothermic direction
- Temp ↓ → exothermic direction
- Conc of reactant ↑ → shift right
- Pressure ↑ → fewer gas molecules side
- Catalyst → no shift (faster equilibrium)
Haber Process
- N₂ + 3H₂ ⇌ 2NH₃ (exothermic forward)
- Temperature: 450°C (compromise)
- Pressure: 200 atm (compromise)
- Catalyst: iron
- High P → more NH₃ (4→2 gas moles)
Common Exam Errors
- Saying equal concs at equilibrium
- Catalyst shifts equilibrium (wrong)
- Not counting gas molecules for pressure
- Missing "closed system" in definition
Key Equations
- N₂ + 3H₂ ⇌ 2NH₃ (Haber process — 4 gas moles → 2 gas moles)
- At equilibrium: rate of forward reaction = rate of reverse reaction
- Le Chatelier: system shifts to oppose any change imposed on it
Practice questions for Equilibrium (HT)
At dynamic equilibrium, which of the following is true?
Explain the effect of increasing temperature on the position of an equilibrium where the forward reaction is exothermic.
Quick recall flashcards
What conditions are needed for equilibrium?
A closed system (nothing can escape) and a reversible reaction
What does 'dynamic equilibrium' mean?
Forward and backward reactions happen at the same rate, so concentrations stay constant