1. Le Châtelier’s Principle

2. Le Châtelier’s Principle
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) + 3H2(g) ↔ CH4(g) + H2O(g)

5. Pressure
Ideal 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) + 3H2(g) ↔ CH4(g) + H2O(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. Think of heat as a reactant or a product.
Temperature
Think of heat as a reactant or a product.
CO(g) + 3H2(g) ↔ CH4(g) + H2O(g) + heat
Is this Exothermic or Endothermic?

8. CO(g) + 3H2(g) ↔ CH4(g) + H2O(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.