Le Chatelier's Principle, Applied

What Equilibrium Actually Means

• Forward and reverse reaction rates are equal at equilibrium
• Concentrations remain constant — not necessarily equal
• Kc = [products] / [reactants]
• Kc > 1 → products are favoured  ·  Kc < 1 → reactants are favoured

Le Chatelier's Principle

Concentration: adding product   → equilibrium shifts LEFT
Temperature:   increasing T      → shifts toward the endothermic direction
Pressure:      increasing P      → shifts toward fewer moles of gas
Catalyst:      speeds up BOTH directions equally — no equilibrium shift

Worked Example — The Haber Process

• N₂ + 3H₂ ⇌ 2NH₃
• Temperature: ~400°C (a compromise between yield and reaction rate)
• Pressure: ~200 atm
• Catalyst: Iron