1. Le Chatelier's Principle
Lesson 3
Le Chatelier's Principle
Gases

2. A(g) + B(g) ⇄ AB(g)
2 particles particle
more pressure less pressure
When the reaction shifts to the right it lowers the pressure
When the reaction shifts to the left it increases the pressure

3. Simulation
A(g) + B(g) ⇄ AB(g)
50 Particles
Shifting right reduces the particles and the pressure

4. A(g) + B(g) ⇄ AB(g)
50 Particles
Shifting right reduces the particles and the pressure

5. A(g) + B(g) ⇄ AB(g)
49 Particles
Shifting right reduces the particles and the pressure

6. A(g) + B(g) ⇄ AB(g)
49 Particles
Shifting right reduces the particles and the pressure

7. A(g) + B(g) ⇄ AB(g)
48 Particles
Shifting right reduces the particles and the pressure

8. A(g) + B(g) ⇄ AB(g)
49 Particles
Shifting left increases the particles and the pressure

9. A(g) + B(g) ⇄ AB(g)
49 Particles
Shifting left increases the particles and the pressure

10. A(g) + B(g) ⇄ AB(g)
50 Particles
Shifting right reduces the particles and the pressure

11. 4HCl(g) + 2O2(g) ⇄ 2H2O(l) + 2Cl2(g)
6 gas particles
2 gas particles
more pressure
less pressure
Shifting left increases the pressure by making more particles.

12. 2SO3(g) ⇄ SO2(g) O2(g)
2 gas particles
3 gas particles
more pressure
less pressure
Shifting right it increases the pressure by making more particles.

13. I2(g) + Cl2(g) ⇄ 2ICl(g)
2 gas particles 2 gas particles
the pressure is the same on both sides
This reaction will not shift with pressure.

14. 6. 1. Increasing the pressure by decreasing the volume shifts the
6.1 Increasing the pressure by decreasing the volume shifts the to the fewest gas molecules. Only (g) count for gas particles.
4HCl (g) O2 (g) ⇄ H2O (l) Cl2 (g) kJ
We decrease the volume
Simulation

15. 6. 1. Increasing the pressure by decreasing the volume shifts the
6.1 Increasing the pressure by decreasing the volume shifts the to the fewest gas molecules. Only (g) count for gas particles.
4HCl (g) O2 (g) ⇄ H2O (l) Cl2 (g) kJ
We decrease the volume

16. 4HCl (g) + 2O2 (g) ⇄ 2H2O (l) + 2Cl2 (g) + 98kJ
6.1 Increasing the pressure by decreasing the volume shifts to the fewest gas molecules. Only (g) count for gas particles.
4HCl (g) O2 (g) ⇄ H2O (l) Cl2 (g) kJ
 We decrease the volume and we increase pressure!
The reaction opposes by shifting to right to decrease the pressure!
All concentrations go up!
All rates go up!

17. We Do We Do Rx Does Shift Volume Pressure Pressure Equation
increase
decrease
increase
3 ⇌ 5
right
decrease
increase
decrease
8 ⇌ 5
right
left
increase
decrease
increase
9 ⇌ 3
decrease
increase
decrease
4 ⇌ 7
left
increase
decrease
increase
0 ⇌ 1
right

18. We Do We Do Rx Does Shift Volume Pressure Pressure Equation
increase
decrease
increase
6 ⇌ 7
right
decrease
increase
decrease
7 ⇌ 2
right
left
increase
decrease
increase
10 ⇌ 8
decrease
increase
decrease
left
40 ⇌ 53
increase
decrease
increase
6 ⇌ 9
right

19. 7 9
5A(g) B(g) ⇌ 4C(g) + 5D(g)
We ⇓ V

20. 7 9
5A(g) B(g) ⇌ 4C(g) + 5D(g)
We ⇓ V

21. 7 9
5A(g) B(g) ⇌ 4C(g) + 5D(g)
We ⇓ V

22. 7 9
5A(g) B(g) ⇌ 4C(g) + 5D(g)
We ⇓ V

23. 7 9 5A(g) + 2B(g) ⇌ 4C(g) + 5D(g) We ⇓ V We ⇑ P
7 9
5A(g) B(g) ⇌ 4C(g) + 5D(g)
We ⇓ V
We ⇑ P
The Reaction opposes ⇓ P
Shifts left

24. 6 5 4A(g) + 2B(g) ⇌ 3C(g) + 2D(g) What volume change shifts right?
6 5
4A(g) B(g) ⇌ 3C(g) + 2D(g)
What volume change shifts right?
We ⇑ P
We ⇓ V

25. 4 7 2A(g) + 2B(g) ⇌ 3C(g) + 4D(g) What volume change shifts right?
4 7
2A(g) B(g) ⇌ 3C(g) + 4D(g)
What volume change shifts right?
We ⇓ P
We ⇑ V

26. 4HCl (g) + 2O2 (g) ⇄ 2H2O (l) + 2Cl2 (g) + 98kJ
Describe the shift in the above equilibrium system for each stress indicated. Describe how [HCl], [O2], and [Cl2] change.
Stress Shift [HCl] [O2] [Cl2]
↑ [HCl] → ↑ ↓ ↑
↓ [O2] ← ↑ ↓ ↓
Add water ― ― ― ―
↑ [Cl2] ← ↑ ↑ ↑ ↓ ↓ ↓
↑ V ←
When the volume increases all concentration go down

27. The Forward and Reverse Rates and Shifting
Explain in terms of the immediate changes to the forward and reverse rates after each stress why each shift occurs
2CO(g) + O2(g) ⇄ 2CO2(g) + energy
4. Volume is decreased
Shift
Forward
Reverse

28. The Forward and Reverse Rates and Shifting
Explain in terms of the immediate changes to the forward and reverse rates after each stress why each shift occurs
2CO(g) + O2(g) ⇄ 2CO2(g) + energy
4. Volume is decreased
Shift
Forward
Reverse 3 2
Pressure increases!
All concentrations go up!
right
All rates go up!
increases by more
increases