Principio di Le Chatelier Le Chatelier's Principle A system at equilibrium responds to disturbance by shifting to oppose it and restore balance aA + bB ⇌ cC + dD Add Reactant e.g. more N₂ N₂ + 3H₂ ⇌ 2NH₃ Raise Temperature endothermic reaction N₂ + O₂ ⇌ 2NO (+ΔH) Increase Pressure compress the vessel N₂ + 3H₂ ⇌ 2NH₃ (4 mol→2) Before After Reactants Products Reactants Products Before After Reactants Products Reactants Products Before After Reactants Products Reactants Products Shifts RIGHT (forward) Shifts RIGHT (toward heat) Shifts to fewer moles of gas Key principle: the system minimises the effect of the imposed change, never eliminates it Haber process: high pressure (favours fewer mol) + high T (rate) + Fe catalyst | Kc unchanged by pressure or catalyst Reazione all'equilibrio sottoposta a tre perturbazioni (aggiunta di un reagente, aumento della temperatura per una reazione endotermica, aumento della pressione) con il conseguente spostamento dell'equilibrio in ciascun caso.
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