1. Do Now Answer the riddle: What comes down but never goes up?
When the bell rings
After the bell (2 min)
Answer the riddle: What comes down but never goes up?
In your seat:
With pen/pencil
With Notebook
With Handout
Silent and ready for Do Now
Still needs Do Now

2. Agenda  Do Now (5 min) Warm Up: (20 min) Notes: Equilibrium (30 min)
Group Practice (10 min)
Independent Practice (15 min)
Exit Slip (5 min)
Closeout (2 min) 
Agenda

3. Unit: Thermodynamics Topic: Equilibrium
Objectives:
Explain what it means for a reaction to be at equilibrium
Predict how changes in temperature, pressure and concentration will affect equilibrium

4. Mood rings use changes in blood circulation to change color
Mood rings use changes in blood circulation to change color. How is this an example of equilibrium?
Guiding question

5. A reaction is spontaneous when:
If a reaction feels hot or cold, is this an open or closed system? Explain.
Warm Up (20 min)
A reaction is spontaneous when:
∆H (energy) = -
∆S (disorder) = +

6. A reaction is spontaneous when:
Would the following reaction occur spontaneously?
I do:
Ca(s) + S(s)  CaS(s) + energy
Warm Up (20 min)
A reaction is spontaneous when:
∆H (energy) = -
∆S (disorder) = +

7. A reaction is spontaneous when:
Would the following reaction occur spontaneously?
We do:
CaS(s) + heat Ca(s) + S(s)
Warm Up (20 min)
A reaction is spontaneous when:
∆H (energy) = -
∆S (disorder) = +

8. A reaction is spontaneous when:
Would the following reaction occur spontaneously?
We do:
20kJ + H2O(s)  H2O(l)
Warm Up (20 min)
A reaction is spontaneous when:
∆H (energy) = -
∆S (disorder) = +

9. A reaction is spontaneous when:
Would the following reaction occur spontaneously?
We do:
H2O(l)  H2O(s) + 20kJ
Warm Up (20 min)
A reaction is spontaneous when:
∆H (energy) = -
∆S (disorder) = +

10. A reaction is spontaneous when:
Would the following reactions occur spontaneously?
You do:
F2(g) + 2Li(s)  2LiF(s)+ energy
NaCl(s) + energy  NaCl(l)
Warm Up (20 min)
A reaction is spontaneous when:
∆H (energy) = -
∆S (disorder) = +

11. Vocabulary and Definitions
Equilibrium: a condition that exists when the forward reaction rate equals the reverse reaction rate such that there appears to be no change in the concentration of products or reactants.
Le Chatelier’s Principle: if equilibrium is disturbed by changing conditions, the position of equilibrium shifts to reestablish an equilibrium
Vocabulary and Definitions

12. KP #1: What is dynamic equilibrium?
In every reaction we have talked about this year, we said
Reactants  Products
We call this the forward reaction
KP #1: What is dynamic equilibrium?
REACTANTS
PRODUCTS

13. KP #1: What is dynamic equilibrium?
But…Sometimes under the right circumstances
Reactants  Products
We call this the reverse reaction
KP #1: What is dynamic equilibrium?
REACTANTS
PRODUCTS

14. KP #1: What is dynamic equilibrium?
When this happens, both reactions occur simultaneously (at the same time)
KP #1: What is dynamic equilibrium?
REACTANTS
PRODUCTS

15. KP #1: What is dynamic equilibrium?
When the rate (pace) of the forward reaction equals the rate of the reverse reaction we call this DYNAMIC EQUILIBRIUM
In other words, reactants make products (forward) at the same speed as the products make reactants (reverse)
KP #1: What is dynamic equilibrium?

16. KP #1: What is dynamic equilibrium?
Represented by:
KP #1: What is dynamic equilibrium? OR

17. KP #1: What is dynamic equilibrium?
Water Wars
Two volunteers
What to watch for:
What happens to the water levels over time
Was there a time when it seemed the levels did not change?
KP #1: What is dynamic equilibrium?

18. KP #2: Le Chatelier’s Principle
Equilibrium can shift
Which means: One direction of the reaction is favored (occurs faster)
3 Factors:
Concentration (amount)
Temperature
Pressure
KP #2: Le Chatelier’s Principle OR

19. KP #3: Predicting changes
Concentration: amount of products/reactants can be added or removed
Away from: the side that is increased
Towards: the side that is decreased
KP #3: Predicting changes
H2O2 H2 + O2

20. KP #3: Predicting changes
Temperature: Can be increased or decreased
Away from: the side with energy or heat when temp
Towards: the side with energy or heat when temp
KP #3: Predicting changes
H2O2 + energy H2 + O2

21. KP #3: Predicting changes
Pressure: Can be increased or decreased
Away from: side with most gas molecules when pressure
Towards: side with most gas molecules when pressure
KP #3: Predicting changes
H2O2(g) H2(g) + O2(g) 1 1 1
2 gas molecules

22. KP #3: Predicting changes
4 Steps
Identify the factor that changes and circle it in the equation
Draw an arrow to show how it changes ( )
Determine the shift and draw the favored direction
Answer the questions
arrow pointing at = increase
arrow pointing away = decrease
KP #3: Predicting changes
H2O2 H2 + O2
Copy steps under your warm up

23. KP #3: Predicting changes
I do: If the concentration of H2O2 is increased, which direction will the equilibrium shift?
What will happen to the concentration of H2 over time?
KP #3: Predicting changes
H2O2 H2 + O2

24. KP #3: Predicting changes
We do: If the concentration of O2 is increased, which direction will the equilibrium shift?
What will happen to the concentration of H2O2 over time?
What about H2?
KP #3: Predicting changes
H2O2 H2 + O2

25. KP #3: Predicting changes
You do: If the concentration of H2O2 is decreased, which direction will the equilibrium shift?
What will happen to the concentration of H2 over time?
KP #3: Predicting changes
H2O2 H2 + O2

26. KP #3: Predicting changes
You do: If the concentration of O2 is decreased, which direction will the equilibrium shift?
What will happen to the concentration of H2O2 over time?
What about H2?
KP #3: Predicting changes
H2O H2 + O2

27. KP #3: Predicting changes
I do: If the temperature is increased during the reaction to the right, which direction will equilibrium shift?
What will happen to the concentration of H2O2?
What about H2?
KP #3: Predicting changes
H2O2 + energy H2 + O2

28. KP #3: Predicting changes
You do: If the temperature is decreased during the reaction to the right, which direction will equilibrium shift?
What will happen to the concentration of H2O2?
What about H2?
KP #3: Predicting changes
H2O2 + energy H2 + O2

29. KP #3: Predicting changes
I do: If the pressure is increased during the reaction to the right, which direction will equilibrium shift?
What will happen to the concentration of H2O2?
What about H2?
KP #3: Predicting changes
H2O2(g) H2(g) + O2(g) 1 1 1
2 gas molecules

30. KP #3: Predicting changes
You do: If the pressure is decreased during the reaction to the right, which direction will equilibrium shift?
What will happen to the concentration of H2O2?
What about H2?
KP #3: Predicting changes
H2O2(g) H2(g) + O2(g) 1 1 1
2 gas molecules

31. Small Group Practice How What 10 minutes Complete practice on handout
C: 1 - 2, on task conversation
H: Ask partners, raise hand, move on to next question until I am available
A: Completing questions
M: In clusters. 3 Hall passes.
P: Answering questions on handout, using notes, head up, discussing in groups, using boxes
10 minutes
Complete practice on handout

32. Independent Practice How What 15 minutes
C: 0 – 1, only on task conversation
H: Raise hand, move on to next question until I am available
A: Completing questions
M: In clusters. 3 Hall passes.
P: Answering questions on notebook paper, using notes, head up, discussing in groups, using boxes
15 minutes
Complete practice on reverse side of notes

33. Exit Slip 2K + S  K2S + Heat If heat is added,
which direction will equilibrium shift?
What will happen to the amount of K2S over time?
What will happen to the amount of S over time?
Exit Slip
Answers on scrap paper
3 minutes
No notes
No conversation