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 What does it mean to achieve equilibrium?
What are some examples of equilibrium?

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
Wear Closed Toe Shoes Wednesday/ Thursday

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

8. Writing Equilibrium Constant Expressions
Complete the inquiry activity at your desk

9. Brainstorm: What does it mean to be in equilibrium?
Balanced

10. Chemical Reactions
We are use to thinking about chemical reactions like this:

11. Chemical Reactions can be Reversible
Some reactions are reversible, where the products can regenerate the original reactants

12. Chemical Equilibrium The forward and reverse reaction rates are equal
Equilibrium DOES NOT mean the concentrations of reactants and products are equal

14. Dynamic Chemical Equilibrium
Chemists refer to equilibrium as dynamic because the reaction does not stop when it reaches equilibrium, but becomes constant
The system is changing but there is no net reaction
In a closed system, almost all reactions will reach equilibrium

15. Equilibrium Constant Notes

16. 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

17. 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

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

19. 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

20. 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

21. 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]
_______________

22. 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)

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

24. 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