Chapter summary
Chemical Equilibria, at a glance
Explain a changing equilibrium, calculate its composition and connect the Haber process to rate and yield.
A-Level 8873, revised syllabus (2026-2027)
Quick revision
Revisit the essentials, then return to an explanation when you need it.
| Question | Reasoning |
|---|---|
| Which way does equilibrium shift? | Use the imposed concentration, gas-volume or temperature change and the balanced equation. |
| Does Kc change? | Only a temperature change changes Kc for the same written reaction. |
| How fast is equilibrium reached? | Use kinetics; a catalyst changes the approach, not the equilibrium composition. |
Kc: equilibrium concentrations, products over reactants, coefficient powers. Convert amounts using the final volume. Link changes by stoichiometry and reject negative concentrations.
Haber: high pressure favours fewer gas moles; lower temperature favours the exothermic equilibrium but slows reaction. Iron gives a faster approach; cooling separates ammonia and reactants are recycled.