Le Chatelier’s Principle

1. Le Chatelier’s Principle Way to predict changes that occur when an equilibrium system is disturbed N2(g) +3H2(g)  2NH3(g) Rate of forward reaction increases until equilibrium is reestablished. Keq remains the same Equilibrium position shifts right • Definition • Changes in concentration • Increase in N2 or H2

2. Le Chatelier’s Principle N2 +3H22NH3 Rate of reverse reaction increases until equilibrium is reestablished Keq stays the same Equilibrium position shifts to the left Equilibrium position shifts to the left Equilibrium position shifts to the right • Changes in Concentration (continued) • Increase in NH3 • Decrease in reactants • Decrease in products

3. Le Chatelier’s Priniciple Changes in Concentration 2H2(g) + O2(g) 2H2O(l) Equilibrium position shifts right No shift in equilibrium position H2O(l) not a dispersed phase • Increase in reactants • Increase in products

4. Le Chatelier’s Principle Changes in Volume N2 +3H22NH3 Pressure increases Equilibrium position will shift to side with fewest dispersed molecules Above reaction shifts right Keq stays the same Equilibrium position shifts to side with most dispersed molecules Above shifts left • Decrease volume of system • Increase in volume

5. Le Chatelier’s Principle Changes in Temp N2 +3H22NH3 + Energy Energy Decreases Equilibrium position will shift to side with less stored chemical energy Above reaction shifts right Keq changes!! Equilibrium position shifts to side with most stored chemical energy Above shifts left • Decrease temperature of system • Increase in temperature