Le Châtelier and
His Principle
Warm-Up
(1) A mixture of H2 and I2 is allowed to react at 448oC. When
equilibrium is established, the concentrations of the participants are
found to be [H2] = 0.46 M, [I2] = 0.39 M, and [HI] = 3.0 M. Calculate
the value of the Keq at 448oC.
H2(g) + I2(g) <=====> 2 HI(g)
(2) Calculate the equilibrium constant, Keq, for the following reaction
at 25 °C, if [NO] = 0.106 M, [O2] = 0.122 M and [NO2]eq = 0.129 M.
2 NO (g) + O2 (g)  2 NO2 (g)
Warm-Up Answers
(1)
(2) Keq = 12.1
Homework Answers
EQUILIBRIUM:
[SO3]2
(1) Keq = ---------------------------------[SO2]3 [O2]
1
(3) Keq = ------------------------------------[H2]2 [O2]
(5) Keq = [CO2]
(2) n/a = all liquids
[CH4] [H2O]
(4) Keq = --------------------------------------------------[H2]3 [CO]
Homework Answers
(6) 0.133
(7) Keq < 1 thus reactants favored
(8) 4.01
(9) 0.50
(10) 1.41 M
(11) 0.599
(12) 9.81 X 10 -3
(0.00981)
Solutions/Acid & Bases
RETEST
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your previous test before taking the retest.
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ATTENDANCE RECOVERY
Last day for attendance recovery is THURSDAY, January 7, 2016!
All forms must be submitted by Friday, January 8, 2106!
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MAKE-UP WORK
ALL make-up work must be submitted by
this Friday, January 8, 2016
The Week Ahead….
Day
Mon / Tues
Wed
What We’ll Be Doing

Unit 11 – Equilibrium
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Unit 11 QUIZ (Grade)
Reference Table Scavenger Hunt (Grade)
Exam Review Day 1
Thurs



Exam Review Packet – Grade Sheet #1
Take/Discuss Released Test (Short Version)
Exam Review Day 2
Fri



Exam Review Packet – Grade Sheet #2
Cumulative Review Demo – Post-Test (Grade)
Exam Review Day 3
Mon



Exam Review Packet – Grade Sheet #3
Take/Discuss Released Test (Long Version)
Exam Review Day 4
Tues

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
Exam Review Packet – Grade Sheet #4
Cumulative Review Activity
Final Exam Reminders
Le Châtelier’s Principle
If a stress is applied to a system at equilibrium,
the system shifts to reduce the stress.
The 3 stresses of Chemistry
1. Concentration
2. Temperature
PRODUCTS
3. Pressure
REACTANTS
Concentration
Increasing the concentration of one of the
reactants or products causes a shift toward the
other side.
Decreasing the concentration of one of the
reactants or products causes a shift toward the
same side.
Temperature
Treat heat as a product for exothermic
Treat heat as a reactant for endothermic
Refer back to rules for concentration
Pressure
Note-only applies if there is an unequal
amount of gases on each side
Increasing the pressure will cause a shift toward
the side with the lower number of moles of gas.
Decreasing the pressure will cause a shift
toward the side with the higher number of
moles of gas.
Learning Team Challenge
N2 (g) +
H2 (g) ⇆
NH3 (g)
Would the equilibrium shift toward the reactants OR products if……
Hydrogen was removed?
Ammonia was added?
Hydrogen was added?
Pressure was increased?
12.6 J + H2 (g) + I2 (g)  2HI (g)
How would the equilibrium shift when the following stresses
are applied to the system?
(1) Add hydrogen iodide
(2) Increase the temperature
(3) Decrease the pressure
(4) Remove Iodine
UNIVERSITY OF EQUILIBRIUM
http://www.education.uoit.ca/lordec/ID_LORDEC/c
hemistry_lechateliers/index.html
CAN YOU GRADUATE
WITH HONORS?
Hawkins’ Wiki Page – January 5 – Click on the Link for University of Equilibrium
- Start with Admissions Requirements
- Complete Years 1 – 4
- Take Final Exam – show Hawkins’ Score
You try!
C2H2 (g) + H2O (g) ⇆ CH3CHO (g)
The above reaction is endothermic, predict the shift in
the equilibrium
(1) You increase CH3CHO
(2) You decrease C2H2
(3) You increase H2O
(4) You decrease the temperature
Goals
You should now be able to…
Predict what side of the reaction will be
favored given a stressor
Exit Ticket
For the equilibrium system
(1) Write the equation for the calculating the equilibrium constant
How will the above reaction shift if:
(2) More chlorine is added?
(3) Pressure is increased (note: all reactants and products are gases)
BONUS: Keq = 35. If the concentrations of PCl5 and PCl3 are 0.025M
and 0.68M respectively, what is the concentration of the Cl2?
HOMEWORK
 Worksheet
Equilibrium: #13
Le Chatelier’s Principle:
ALL (1 – 5) – omit 2 D
UNIT 11 QUIZ TOMORROW !!
 BRING YOUR ORGANIZED NOTEBOOK
TOMORROW TO BEGIN EXAM REVIEW!!