Download Equilibrium (PowerPoint) West Coast 2015

Chemistry Teachable Tidbit
Summer Institute
Randy, Brandi, Casey, Matt, Teresa
Teaching Tidbit Context
Our audience consists students in the second
semester of a general chemistry course.
Typical Units
Unit 1 – Intermolecular forces and Solutions
Unit 2 – Kinetics and Equilibrium
Unit 3 – Thermodynamics
Learning Goal
Students will understand and appreciate the
relationship between kinetics and equilibrium.
Learning Objectives
1. Generate a model that describes a dynamic
equilibrium system
2. Compare and contrast concentration versus
time graphs for an equilibrium system
3. Generate an equilibrium expression for a
reaction given the rate law expressions
4. Relate the individual rate constants to the
equilibrium constant expression
Concentration Change over time
Reaction: A
t=0 min
t=10 min
B
t=20 min
Imagine you are in your chemistry lab completing an
experiment. Your reaction has run for 20 minutes and you have
the above data. Each beaker above shows the concentrations of
A and B.
As a Group
1. Draw a correctly formatted graph showing the change in
concentration of A and B over time.
2. Predict: Draw the reaction beaker at t = 30 minutes.
Concentration Change over time
Reaction: A
t=0 min
t=10 min
t=20 min
B
t=30 min
t=100 min
You then allow your reaction to go for up to 100
minutes. Modify your graph to include the new
data. Discuss the change of concentration of A
and B over time.
Concentration Change over time
Reaction: A
t=0 min
t=10 min
t=20 min
B
t=30 min
t=100 min
As the reaction progresses, focus on the black outlined
molecule converting between A and B.
4. Discuss within your group whether the reaction has
stopped at 20 minutes. At 100 minutes?
Dynamic Equilibrium
At equilibrium, which of the following
statements is true about the rates?
Reaction: A
A.
B.
C.
D.
B
Rate of forward rxn > Rate of reverse rxn
Rate of forward rxn = Rate of reverse rxn
Rate of forward rxn < Rate of reverse rxn
Rate of forward rxn =0, rate of reverse rxn = 0
SUMMATIVE ASSESSMENT #1 (High level HOC)
Assessing Learning Objective 1 - Generate a model that
describes a dynamic equilibrium system
1. Consider the kinetic data produced by monitoring the
reversible conversion of Molecule A to Molecule B over time.
A
B
a) Propose a balanced chemical equation to explain these data.
b) Generate the equilibrium expression for your proposed chemical
reaction.
c) What concentrations would you expect for A and B at equilibrium?
SUMMATIVE ASSESSMENT #2 (HOC)
Assessing Learning Objective 2 - Compare and contrast
concentration versus time graphs for an equilibrium system
2. a) For the reaction below, circle the graph that best describes the change
in concentration over time where Keq = 2.0
Concentration
Time
Time
Concentration
B
Concentration
A
B
Concentration
Reaction: A
Time
Time
b) Explain the reasoning behind your choice.
SUMMATIVE ASSESSMENT #3 (LOC)
Assessing Learning Objective 1 - Generate a model that
describes a dynamic equilibrium system
A
B
B
Concentration
Reaction: A
0
10 Time20
1. Using the Graph above:
a. What time are the concentrations of A and B equal?
b. What time has the reaction reached equilibrium?
Inclusive Teaching Strategies
1. Engage more learning styles by:
• using visual, auditory and tactile learning opportunities
2. Engage more personality types by:
• working in small groups
• asking one group member to report out
3. Make material accessible to include more abilities by:
• simple diagrams without “scary molecules”
• color choices for teaching materials
Normal Color Vision
Red-Blind/Protanopia Vision
http://www.color-blindness.com/coblis-color-blindness-simulator/