1. Equilibrium Notes 1 1 1 1

2. Le Chatelier’s Principle
When a reversible chemical reaction at equilibrium undergoes a change, the system will work to undo that change.

3. Le Châtelier’s Principle
Change in Reactant or Product Concentrations
Add Reactant = Shift to Right
Add Product = Shift to Left
Removing reactant = Shift to Left
Removing product = Shift to Right
We illustrate the concept with the industrial preparation of ammonia

4. Le Châtelier’s Principle
Change in Reactant or Product Concentrations
Consider the Haber process
If H2 is added while the system is at equilibrium, the system must respond to counteract the added H2 (by Le Châtelier).
That is, the system must consume the H2 and produce products until a new equilibrium is established.
Therefore, [H2] and [N2] will decrease and [NH3] increases.

5. Changes in Temperature
- If heat is added to the system, the equilibrium will shift to reduce heat.
- If heat is taken from the system, the equilibrium will shift to increase heat.

7. Changes in Pressure
- ONLY affects gases (g).
- Increase pressure in system = shift towards side with LESS mols of gas.
- Decrease pressure in the system = shift towards side with MORE mols of gas.
- If NO GAS PRESENT, changing pressure DOES NOT effect equilibrium and NO SHIFT occurs.

8. Changes in Pressure 2A (g) B(g) Increase Pressure Decrease Pressure
B is favored b/c less mols = less space needed for GASES
Initial Pressure
A is favored b/c more space = more room for more mols of GAS