1. Writing Equilibrium Constant Expressions

2. Evaluation/Assessment:
Objective:
Today I will be able to:
Write and solve the equilibrium constant expression for a reaction
Determine if a reaction is reactant or product favored
Evaluation/Assessment:
Informal assessment: Monitoring student interactions and questions as they complete the Equilibrium constant practice.
Formal assessment: Analyzing student responses to the practice and the exit ticket
Common Core Connection
Build Strong Content Knowledge
Reason abstractly and quantitatively
Make sense of problems and persevere in solving them

3. Lesson Sequence Evaluate: Warm – Up
Engage/Explore: Writing Equilibrium Constant Expression Inquiry
Explain: Equilibrium Constant Notes
Elaborate: Equilibrium Constant Practice
Evaluate: Exit Ticket

4. Warm - Up
Write the equilibrium constant expression for the following reactions
a. O3 (g) + NO(g) → O2(g) + NO2(g)
b. 2CO(g) + O2(g) → 2CO2(g)
c. NH4NO3(s) → N2O(g) + 2H2O(l)
d. 2H2O(g) → 2H2(g) + O2(g)

5. Objective Today I will be able to:
Write and solve the equilibrium constant expression for a reaction
Determine if a reaction is reactant or product favored

6. Homework
Finish Equilibrium Practice Problems

7. Agenda Warm – Up Equilibrium Constant Expression Inquiry
Equilibrium Constant Notes
Equilibrium Constant Practice
Exit Ticket

8. Equilibrium Constant Notes

9. Equilibrium Constant
Expresses the relative concentrations of reactants and products at equilibrium by using an “equilibrium constant” – Keq
a A + b B  c C + d D

10. Equilibrium Constant
Only include gases and aqueous solutions when writing equilibrium constants
Solids and liquids are not included
They can be represented with a [1] or left out entirely

11. Types of Equilibrium Problems
Qualitative
Keq < 1, then the reaction is reactant-favored at equilibrium
COCl2(g)  CO(g) + Cl2(g)
Keq = 2.2 x 10-10
Reactant-favored

12. Types of Equilibrium Problems
Keq > 1, then the reaction is product- favored at equilibrium
2 NO2(g)  N2O4(g)
Keq = 2.15 x 102
Product-favored

13. Keq and Stresses on the system
Keq does not change with change in concentration
It will change based on change in temperature and change of pressure

14. Types of Equilibrium Problems
Quantitative (uses the Keq equation)
Write the equilibrium expression for the following reaction
2 SO2(g) + O2(g)  2 SO3(g)
[SO3]2
[SO2]2 [O2]
_______________

15. Types of Equilibrium Problems
If M of O2, M of SO2 and M of SO3 at equilibrium, calculate Keq
[SO3]2
[SO2]2 [O2]
[.00140]2
[.0250]2 [.0172]
_______________
_______________
Keq = .18 (reactant favored)

16. Equilibrium Constant Practice
Complete the practice at your desk. Whatever you do not finish will become your homework

17. Le Chatelier’s Principle Review
Answer the following questions with a partner

18. Determine whether the following statements are true or false
At equilibrium:
The rate of the forward reaction equals the rate of the reverse reaction
The concentration of reactants and products is always equal
The concentrations of reactants and products remain constant

19. Answers
True
False

20. True or False
Le Chatelier’s principle describes how a system at equilibrium restores equilibrium after it has been “stressed”

21. Answer
True

22. What different “stresses” can be applied to a system?
Adding/ Removing Reactants
Adding/ Removing Products
Changing Pressure
Changing Volume
Changing Temperature

23. Concept Check Given the reaction is at equilibrium:
2H2 (g) + O2 (g)  2H2O (g) + heat
Which direction will the equilibrium shift when:
When more hydrogen gas is added
The volume of the system is doubled
Water vapor is removed from the system

24. 2 A (g) + B (g)  C (g) + X kJ
For the reaction above complete the table below
Stress
Direction of Shift
[A]
[B]
[C]
Add B
____
Add C
___
Remove A
Remove C
Increase Pressure
Increase Volume
Decrease Temp

25. 2 A (g) + B (g)  C (g) + X kJ
For the reaction above complete the table below
Stress
Direction of Shift
[A]
[B]
[C]
Add B
right
decrease
____
increase
Add C
Left
Increase
___
Remove A
Decrease
Remove C
Right
Increase Pressure
Increase Volume
Decrease Temp

26. 2NH3(g) kJ↔ N2(g) + 3H2(g)
For the reaction above complete the table below
Stress
Direction of Shift
[NH3]
[N2]
[H2]
Keq
Add [N2]
____
Add NH3
___
Remove NH3
Remove hydrogen
Increase Pressure
Increase Volume
Decrease Temp

27. Exit Ticket Given the following reaction:
Use Le Chatelier’s principle to determine what would happen if the following changes were made
Increase the concentration of N2
Increase the concentration of NH3
Remove NH3 from the reaction after it is made