1. LeChatelier’s Principle

2. Le Chatelier's Principle
If a system is disturbed by a change in temperature, pressure, or the concentration of one of the components, the system will shift its equilibrium position so as to counteract the effect of the disturbance.
Changing the concentration of species:
N2(g) + 3H2(g) ↔ 2 NH3(g)
add N2 or H2 →
add NH3 ←
remove N2 or H2 ←
remove NH3 →
Does not affect the value of K!!

3. If pressure is changed by a change in volume, the system will shift to minimize the pressure change. However, changing the pressure by adding an inert gas has no effect on the equilibrium since it does not affect the partial pressures of the gases.
N2(g) + 3 H2(g) ↔ 2 NH3(g)
increase volume ←
decrease volume →
Does not affect the value of K!

4. Effect of temperature:
endothermic: reactants + heat ↔ products
If T ↑then K ↑
exothermic: reactants ↔ products + heat
If T ↑then K ↓
K does change!

5. N2O4(g) ↔ 2 NO2(g) ΔH = 58.0
What happens if the temperature decreases?
Catalysts will not change K, they only change the rate of the reaction.

6. Watch this animations of LeChatelier’s principle
Watch this music video
Here is the quiz