Equilibrium · expressions and response
Understand Kc
Practise Kc expressions, then use the Haber model to test changes in concentration, pressure, temperature and catalyst. For full Kc and Kp calculations, use the linked equilibrium sets.
Dynamic equilibrium model
N₂(g) + 3H₂(g) ⇌ 2NH₃(g)
Exothermic forward reaction, ΔH ≈ −92 kJ mol⁻¹. This teaching model uses illustrative Kc values while keeping every shift and equilibrium calculation consistent.
Equilibrium concentrations
System data
- Volume
- 10.0 dm³
- Temperature
- 400 K
- Kc at this temperature
- 0.500
- Current Qc
- 0.500
Use the expression, then follow the calculation chain
Start with the equilibrium amounts, convert them to concentration or partial pressure, then calculate Kc or Kp. The feedback identifies which step produced a characteristic wrong result.
Kc and Qc
I’d keep these two quantities separate. Kc is fixed for a given reaction at a given temperature. Qc describes the mixture at the current moment. After a disturbance, the system shifts until Qc equals Kc again. Kc only changes with temperature.