1. Le Châtelier’s Principle

2. If a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress. Stress is anything that upsets equilibrium – concentration, pressure, or temperature.

3. Concentration Measure of molarity (moles/L) If you ↑ concentration of a reactant, equilibrium will shift toward the products. If you ↓ concentration of a reactant, equilibrium will shift toward the reactants.

4. CO(g) + 3H 2 (g) ↔ CH 4 (g) + H 2 O(g) CO(g) H 2 O(g)

5. Pressure PV=nRTIdeal Gas Law: PV=nRT If ↑ P then ↑ n, which means more number of atoms. If ↑ P, then the equilibrium will shift toward the side with fewer moles of gas.

6. CO(g) + 3H 2 (g) ↔ CH 4 (g) + H 2 O(g) 4 moles of gas 2 moles of gas Note: If moles of gaseous reactant = moles of gaseous product, then no shift in equilibrium will occur from a change in pressure

7. Temperature Think of heat as a reactant or a product. CO(g) + 3H 2 (g) ↔ CH 4 (g) + H 2 O(g) ΔH = -206.5kJ Is this Exothermic or Endothermic? Will heat be a reactant or product?

8. heat CO(g) + 3H 2 (g) ↔ CH 4 (g) + H 2 O(g) + heat

9. Le Châtelier’s Principle If a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress. – Concentration – Pressure – Temperature Note: Only temperature affects K. The larger the value of K, the more product at equilibrium.