Lesson Outline for Lesson #3 – Unit #9
Candidate: Olexandr Andriyashchenko
Date: 15 February, 2016
Lesson Part
Grade level: 11th - 12th AP CHEM 201 chemistry course
Class topic and central focus: oxidation states of elements in
redox species and their roles in real world.
Activity description/Teacher does
Students do
Title
Balancing redox reactions.
NGSS: HS-PS1-7
Use mathematical representations to support the claim that atoms […] are conserved during a
chemical reaction.
Washington Science K-12 Standard: 9-12 APPF
It is important for all citizens to apply science and technology to critical issues that influence society.
(Performance Expectations: Critically analyze scientific information in current events to make
personal choices or to understand public-policy decisions).
EARL: #4
Central Focus (CF) Assigning oxidation numbers for redox species and their place in real world.
Academic Language Half-reactions, potassium permanganate, oxalate, sodium thiosulfate, iodine, sodium iodate, iodide,
starch, sodium sulfide, citric acid, kidneys, titration, electrons, charge, water, redox, reactions,
reduction, reducing agent, oxidation, oxidizing agent.
I can assign oxidation numbers in elements within a species and
identify reducing and oxidizing agent in a redox reaction.
Standard
Learning Target
(LT)
I can describe the real-life applications of redox species.
I can “use a chemical equation to illustrate how the atoms in
molecules are arranged before and after a reaction.” (Washington
K-12 standards)
Engage (video, review, thoughts), (~20 min.).
Greet students and announce that today we will be exploring real
world applications of redox reactions and species and that we start
with two videos of iodine clock reactions. (Engage).
Read the standard: Washington Science K-12 Standard: 9-12 APPF Listen.
“It is important for all citizens to apply science and technology to
critical issues that influence society.”
Have students read LTs.
Instruction (e.g. State that today with chemical equations we are illustrating
inquiry, preview, changes in arrangement of atoms before and after a reaction to
review, etc.)
fulfill our 3rd LT.
Show the video of iodine clock reaction. (Engage).
https://www.youtube.com/watch?v=I4SZsFbZFnY
Read LTs
Listen.
Watch the video.
Ask students to brainstorm and think collaboratively with a partner Share thoughts.
for a few minutes what reactions take place in this demonstration.
Also ask students to return their worksheets from yesterday to get
a stamp for homework completeness. (Engage).
While students brainstorm stamp and collect worksheets.
(Engage).
Return worksheets.
After you finish collecting have students explain what happened in Speak up and explain.
the video. (Engage).
Explain the setup of and mechanism of this Presto Iodine Clock
Listen and take notes.
reaction and instruct students to take notes. Emphasize the role of
iodine in this demonstration:
1. Iodide forms in slow reaction between the iodate and sulfite:
IO3− + 3 SO3−2 → I− + 3 SO4−2 (Rate-determining) step.
2. Iodate in excess will oxidize the iodide generated above to form
iodine: IO3− + 3 I− + 6 H+ → 2 I2 + 3 H2O
3. But iodine is reduced immediately back to iodide by the sulfite:
I2 + SO3−2 + H2O → 2 I− + SO4−2 + 2 H+
4. When sulfite (SO3−2) is fully consumed, the iodine (I2) will survive
to form the dark blue complex with starch.
Ask students if they have any questions about the mechanism of
iodine clock reaction.
Listen and watch the video.
Show the slow motion video of iodine clock reaction with addition
of sodium thiosulfate and state that we are going to focus on what
is happening when sodium thiosulfate is added. (Explore-Explain).
https://www.youtube.com/watch?v=s2np2PaaWtU
Collaboratively assign oxidation
State that the solution turns clear with stirring because of
consumption of iodine by sodium thiosulfate. Project this reaction numbers and identify reducing
and ask students to assign oxidation numbers and identify reducing and oxidizing agent.
and oxidizing agent collaboratively in their notebooks. (ExploreExplain).
Explore (watching and/or scaffolding), (during Engage).
Circulate around the room and watch students assigning oxidation
Informal states and identifying reducing and oxidizing agent.
Assessment Help and direct them if needed so that everyone has accomplished
the task. (Explore).
Practice Activity
or
Support
Collaboratively assign oxidation
numbers and identify reducing
and oxidizing agent. Ask questions
if needed.
Explore (assigning oxidation numbers), (~10 min.).
Mention that we already saw the use of permanganate in oxidation Watch the titration.
of glycerin. Project and demonstrate the following titration redox
reaction between permanganate and oxalate ions:
2MnO4- (aq) + 5C2O42- (aq)  2Mn2+ (aq) + 10CO2 (aq) + 8H20 (l) (Explore).
Explain the role of permanganate ion and why the color changes.
Tell students to copy it down, and collaboratively in groups assign
oxidation states and identify reducing and oxidizing agents.
Copy the reaction and work
collaboratively in groups.
(Explore-Explain).
Explore (watching and scaffolding), (during Explore).
Circulate around the room and watch students assigning oxidation
states and identifying reducing and oxidizing agent.
Informal Help and direct them if needed so that everyone has accomplished
Assessment the task. Distribute worksheet #3 (Explore).
Collaboratively assign oxidation
numbers and identify reducing
and oxidizing agent. Get
worksheet #3. Ask questions if
needed.
Explain (lecturing and brainstorming), (~15 min.).
Announce that we are going to explore the roles of oxalate and
Listen.
permanganate in medicine and health and instruct students to take
notes. (Explain).
Practice Activity
or
Support
Lecture for ~5 min. on oxalate and its links with kidney stones and
that we should avoid eating French fries and potato chips.
Listen and take notes.
Lecture for ~5 min. on medicinal uses of permanganate.
Listen and take notes.
Ask students to collaboratively explain the mechanism of oxalate Brainstorm collaboratively.
crystals formation in kidneys and to come up with explanations
why permanganate might kill bacteria, and to write their thoughts
in worksheet #3. (Explore-Explain).
Informal Explain (watching), (during Explain).
Assessment Circulate around the room and watch students discussing and
Discuss collaboratively and ask
explaining. Help them if needed. (Explain).
questions if needed.
Extend/Elaborate (balancing new reaction), (~10 min.).
Announce that the worksheet is due tomorrow.
Practice Activity
or
Support
Instruct students to complete Reflection section of the worksheet
individually in class as completely as possible and Homework
section at home and bring worksheets next day. Students who try
answering Reflection section get green stamp and those who do
not the red stamp. This is done for future grade on completeness
of work. (Evaluate).
Closure Evaluate/Reflect (reflection), (during Extend/Elaborate).
Assessment of Circulate in class, watch students working on Reflection section,
Student Voice and stamp their worksheets.
Reflection section:
1. What was confusing to me?
2. What was clear? What have I understood?
3. What did I learn from today’s lesson?
4. How can high consumption of fries and potato chips impact
my health and why?
5. How can I use permanganate for my own health benefits?
6. Rate yourself on your confidence of your understanding of
Learning Targets. Explain your self-rating. (Evaluate).
Listen.
Students complete Reflection
section and get a stamp.
Listen.
Students complete Reflection
section and get a stamp.
Teacher circulates around the room prior to the bell ring and
stamps students’ worksheets.
Students show teacher their
reflections and get stamps.
References:
Clark, D. (2014, September 30). The 3 Ultimate Uses Of Potassium Permanganate. Retrieved 15 February,
2016, from http://www.technology.org/2014/09/30/3-ultimate-uses-potassium-permanganate/
Iodine clock reaction. (2016, February 12). Retrieved 15 February, 2016, from
https://en.wikipedia.org/wiki/Iodine_clock_reaction
This lesson is for 55 minutes.
Assumptions: an instructor has already taught concepts of balancing redox reactions by half-reaction method and
students are familiar with these terms: half-reaction, proton (H+), hydroxide (OH-), redox, reduced, reducing agent,
oxidized, oxidizing agent.
Expectations: students will attempt Reflection section of the worksheet in class.