COURSE: Grade 12 Chemistry, University Preparation Level
Curriculum: What will students learn?
Unit of Study: Electrochemistry
Summary: The focus of this
unit is to demonstrate an
understanding
of
redox
reactions in terms of the
electron transfer and change in
oxidation number. Students
will learn the functioning of
the components in electric
cells. They will learn about
corrosion as an electrochemical process and corrosion
inhibiting techniques. They
will perform experiments on
redox reactions and know how
to balance these reactions.
They will know how to predict
the spontaneity of the reaction.
They will be able to describe
examples of common galvanic
cell
and
evaluate
their
environmental
and
social
impact. .
COURSE CODE: SCH4U
Overall Expectations:
A1. demonstrate scientific investigation skills (related to both inquiry and research) in the
four areas
of skills (initiating and planning, performing and recording, analysing and interpreting,
and communicating);
A2. identify and describe careers related to the fields of science under study, and describe
the contributions of scientists, including Canadians, to those fields.
F1. analyse technologies and processes relating to electrochemistry, and their implications
for
society, health and safety, and the environment;
F2. investigate oxidation-reduction reactions using a galvanic cell, and analyse
electrochemical
reactions in qualitative and quantitative terms;
F3. demonstrate an understanding of the principles of oxidation-reduction reactions and
the many
practical applications of electrochemistry
Key Questions:
- What is electrochemistry?
- What are the two main aspects of electrochemistry?
- Give one example of each from real life.
- How does electrochemistry affect health, environment, health and society?
The basic understanding of oxidation and reduction is the key idea in this unit. When
teaching the redox reactions, be sure to draw attention to the concept that the type of
chemical reaction depends on the nature of the reactants (i.e. metal loses electron/s and
non-metal gains electron/s).
1
Designing the Learning
Note: A Day is one 75 minute period.
Learning Skills (LS) Key:
R = Responsibility, O = Organization, IW = Individual Work, C = Collaboration, I = Initiative, SR = Self-Regulation
The timeliness of all submissions (within timelines appropriate to the needs of individual students) and behavior in particular activity
will be considered as part of the Responsibility skill.
Cluster/Topic
Day
Overview and 1
Introduction
to oxidation
and reduction
reactions
Concept/Subtopic with Learning Goals Teaching
for Each Lesson
Strategies
Introduction: After giving an overview of
the unit, lesson begins by introducing the
concepts of oxidation and reduction.
By the end of the lesson, students will be
able to explain “what are oxidation and
reduction reactions?”
2
&
Learning Assessment (A) and Expectation
Evaluation (E);
s Addressed
Learning
Skills
Assessment
Whole-Class Brainstorm on (A:
Diagnostic) F2.1
oxidation
and
reduction brainstormed
reaction and their example responses. Questions
from daily life.
regarding
demonstration.
Lecture on oxidation and
reduction reactions, net ionic LS
reactions, spectator ions, SR and R (during
oxidized ion, reduced ion.
demonstration)
MEMORY TIP: LEO the
lion says GEO
(Note:
see
also
DEMONSTRATION:
evaluation
plan
Oxidation of Glycerin by regarding
Potassium Permanganate - An assessments
and
easy
and
dramatic evaluations)
demonstration of a redox
reaction.
Reading text from Nelson
Chemistry 12 University
Preparation textbook (pg 652-
656, YEAR 2003)
Determining oxidation numbers and how to Lecture
on
oxidation (A) On the basis of F2.1
represent them (with + or – signs)
numbers and states.
practice
sheet
A1.12
responses
By the end of the lesson, students will be Practice
Sheet
1
on
LS
able to determine oxidation numbers of determination of oxidation
IW (during practice
species in ions, and molecules.
number
sheets)
Oxidation
numbers and
Redox
Reactions
2
Recognizing Redox Reactions
By the end of the lesson, students will be
able to
- Recognize redox reactions.
- Explain oxidation in term of
electron change.
- Explain reduction in term of
electron change.
- Define and identify oxidizing and
reducing agents.
- Define and identify substance being
oxidized and reduced.
- Write examples of redox reactions.
Watch video on oxidation and (A)Student responses F2.1
reduction of Ag and S.
during
SMART F2.2
Board and board
(http://www.youtube.com/wat work
A1.12
ch?v=a6RR4kPsnlE)
(A) On the basis of
Lecture
(brief):
includes Practice sheet 2
introduction
of
redox (E) Assignment sheet
reactions, examples of redox 1
reactions from physical and
biological systems.
LS:
Review of examples using
C, SR and R (during
SMART Board lessons on
research work)
redox reactions
IW (during practice
(http://exchange.smarttech.co sheets)
m/details.html?id=2d03db06a962-49a5-a3e6Homework:
6b6885629699) and board
assignment sheet 1
examples of redox reactions
(for homework)
Practice sheet 2 (for class
work) on redox reactions.
Students in a group of 4 will
do research on “what is the
3
difference
in
operation
between the Breathalyzer and
Intoxilyzer and what their
importance in police force is?
How redox reactions are
involved?
Reading text from Nelson
Chemistry 12 University
Preparation textbook (pg 657663, Year 2003)
Oxidation
Number
Method
Half-Reaction
Method
4
3
4
Balancing
Redox
Equations
Oxidation number method
using
Lecture and chalk board
work
Practice sheet 3 (for class
By the end of the lesson, students will be work) on balancing of redox
able to:
reactions using oxidation
- Write steps for balancing redox number method.
reactions using oxidation number
method.
- Write word and balance redox reactions Reading text from Nelson
Chemistry 12 University
using oxidation number method.
Preparation textbook (pg 664668, Year 2003)
Balancing Redox Equations using HalfReaction Method
Lecture and chalk board
work
Practice sheet 4 (for class
By the end of the lesson, students will be work) on balancing of redox
able to:
reactions using Half-Reaction
- Write steps for balancing redox Method.
reactions using Half-Reaction Method.
(A)
Handprint:
Draw your handprint.
In each finger, write
one thing learned
today.
(A) On the basis of
Practice sheet
F2.1
F2.2
F2.3
F3.1
A1.1
A1.8
A1.12
LS:
SR (during chalk
board work)
IW (during practice
sheets)
(E) QUIZ
F2.1
F2.2
(A) On the basis of F2.3
Practice sheet
F3.1
(E) assignment sheet
(for homework)
(A)
FLAG
IT A1.1
(Students will use A1.8
-
Write word and balance redox reactions
using Half-Reaction Method
(Note: short quiz at start of class
relating find the missing step in
balancing the Redox Reactions using
oxidation number method and balance
the given redox reaction).
Reading text from Nelson
Chemistry 12 University
Preparation textbook (pg 668673, Year 2003)
this strategy to help A1.12
them
remember
information that is
important to them.
They will “flag” their
ideas on sticky notes
or flag die cut. They
will
write
some
important
points
regarding balancing
of reactions).
LS:
SR
(reflection
question on quiz
related to level of
readiness and steps
taken/to improve; be
sure you have made
note of students who
have sought extra
help in/outside of
class to this point)
(B) IW (On the basis
of Practice sheet)
Homework:
assignment sheet 2
(for homework)
Predicting
Redox
5
5
Teacher Demonstrations:
Lecture (brief)
Zn strip dip in CuSO4 solution: blue color Students
will
(A)
Safe
watch appropriate
and Lab:
lab F2.2
reactions
of the CuSO4 solution will fade in some
time.
Cu strip dip in ZnSO4 solution: No
reaction.
simulation on activity series
online
(http://group.chem.iastate.edu
/Greenbowe/sections/projectf
older/flashfiles/redox/home.ht
ml)
Students in small groups
perform small experiments
to
investigate
relative
reactivity of metals.
Building
Redox
Table:
Several
groups
of
experimental evidence are
combined to make one larger
table.
By the end of the lesson, students will be
able to:
- Use experimental results to identify
trends in the reactivity of the metal.
- Arrange different metals in the order of
decreasing reactivity (activity series)
- Predict the spontaneity of the redox
reactions on the basis of their experimental
results.
Reading text from Nelson
Chemistry 12 University
Preparation textbook (pg 668673, Year 2003)
Students in a group of 4 will
discuss “When aluminum
pots are used for cooking,
small pits often develop in the
metal. Use your knowledge of
redox reactions to explain the
formation of these pits.
Suggest why this might be a
slow process.”
6
technique; chart of F2.3
results/observations
F3.1
(A) Class discussion A1.2
of findings
A1.4
A1.5
A1.6
LS:
R, O, C and SR A1.7
(manages
own A1.8
behavior during lab)
A1.9
C, SR, R and I A1.10
(works well with lab A1.11
partner; shares space A1.12
and resources with
other groups)
Discussion
A1.9
A1.11
Electrochemical Cells
7
6
Electrochemical Cells,
working and properties
their
design, Lecture on Electrochemical (A)
Think-PairCells, their design, working Share responses
and properties
(A) Create flashcard
View
simulation
of for Electrochemical
Electrochemical Cells online Cell.
By the end of the lesson, students will be http://group.chem.iastate.edu/
able to:
Greenbowe/sections/projectfo LS:
- describe electrochemical cells
lder/flashfiles/electroChem/vo I (participates in
- define anode and cathode
ltaicCell20.html
predict-observeexplain
with
a
- Explain internal and external circuit.
- write and balanced chemical equations Think-Pair-Share Predict- positive attitude; does
Observe-Explain: What do not just wait for
occurring at anode and cathode
they
need
to
design answers to be given)
- explain the function of salt bridge
Electrochemical Cells?
- write cell notation
- list properties of Electrochemical Cells
Reading text from Nelson
Chemistry 12 University
Preparation textbook (pg 695700, Year 2003)
F2.5
F3.2
A1.7
A1.8
A1.10
A1.11
A1.12
Standard
Cells and
Electrode
Potentials
7
Standard Cells, Electrode Potentials.
Calculation of Standard electrode
potentials.
Calculation of cell potential under nonstandard conditions
Predicting the spontaneity of the redox
reaction on the basis of Standard cell
potential.
Practice of numericals.
Lecture and some learning (A) “Every pupil
response” responses
tips.
(E) Assignment sheet
Every pupil response: Each
3 responses
pupil receives a pink and (LS)
yellow card. Each color I (during EVERY
represents a specific response. PUPIL RESPONSE)
Students raise the card to SR
(maintain
provide the correct response discipline in the class
to a teacher directed question during the activity)
(see Resources).
Reading text from Nelson Assignment sheet 3
Chemistry 12 University responses
(for
Preparation textbook (pg 701- homework)
By the end of the lesson, students will be 707, Year 2003)
able to
- calculate standard cell potential
- predict the spontaneity of the redox
reaction on the basis of their
calculations
- know how to build a galvanic cell and
measure its cell potential
- describe galvanic cells in terms of
oxidation and reduction half-cells
whose voltages can be used to
determine overall cell potential.
8
F2.6
F3.3
F3.4
A1.12
A1.13
Lab on
Electrochemical cells
8
Quiz before the commencement of the
practical lab on standard cell potential.
Lab Activity: The purpose of this activity
is to build a galvanic cell and measure its
cell potential
By the end of the lesson, students will be
able to:
- build a galvanic cell and measure its cell
potential.
-draw well labeled diagrams of the
galvanic cell showing half-cell reactions,
the direction of electron flow, anode
,cathode, the cell potential and the
direction of ion movement.
-explain
some
applications
of
electrochemistry in common industrial
processes.
9
Cells and
batteries
9
Test on all the topics studied so far (1hour
duration)
Students perform lab to build
several galvanic cells and
write out the two halfreactions
for
each
electrochemical cell they
created.
(E) Quiz and lab F2.1
reports
F2.4
F2.5
(A)
Safe
and F3.2
appropriate
lab F3.3
technique, chart of F3.5
results
and
observations.
A1.2
A1.4
A1.5
LS:
A1.6
SR,R, IW (manages A1.8
own behavior during A1.11
lab)
A1.12
O (organize their lab A1.13
report in an effective
manner)
C (works well with
lab partner; share
space and resources
with other groups)
(E) On the basis of
test.
LS:
R and SR (not to
copy during test)
properties Lecture (brief)
Teacher will ask the students
about electrochemical cells
and will proceed to batteries.
By the end of the lesson, students will be
 Able to define batteries.
 Differentiate batteries and cells
 Differentiate between electric current
and voltage.
 Enlist differences between primary and
secondary cells.
Basic cell design and
(remaining time period)
10
Lecture contd. (on fuel cells, The Ballard Lecture on different types of
Fuel Cell, Aluminum-Air Cell, Large – Consumer, Commercial and
Scale Commercial and Industrial Fuel Industrial Cells.
Cells)
Reading text from Nelson
Chemistry 12 University
By the end of the lesson, students will be
Preparation textbook (pg 685694, Year 2003)
 State advantages and disadvantages of
fuel cells, The Ballard Fuel Cell,  Students will watch movie
Aluminum-Air Cell, Large – Scale
on
fuel
cells
Commercial and Industrial Fuel Cells.
(http://www.youtube.com/
 Explain the viability of using
watch?v=oy8dzOB-Ykg)
electrochemical
technologies
as
and research on using
alternate source of energy.
electrochemical
 Describe their potential impact on
technologies as alternate
society and the environment.
source of energy and find
their potential impact on
society
and
the
10
(A) Students’
responses
LS:
I ( to answer
teacher ’s questions)
A1.1
F3.2
(A) on the basis of F1.1
students’ finding
F1.2
F3.5
LS:
R (manages own
behavior
during A1.1
research)
A1.3
A1.7
A1.9
A1.10
A1.11
environment. ( students
can use library books,
computers, magazines etc)
11
Contd. Research on the same topic and
submit their lab reports on the following
queries:
 What are the social impacts of the
batteries?
 What are the possible environmental
impacts of the battery?
 How can electrochemical technologies
be used as alternate source of energy?
 How should these batteries be
discarded to protect the environment?
Take students to library or
computer lab; call students up
individually to discuss how
their research is going
(A) Rough notes
(present,
thorough,
documented,
organized)
A1.3
A1.7
A1.9
A1.10
F1.1
LS:
O, SR (research notes F1.2
organized,
student
has started research
and has a plan for
continuing)
IW (makes good use
of
research
opportunity)
Developing an 12
Electric Cell
11
Planning the design of an electric cell Students will use aluminum
from used aluminum soft-drink can or soft-drink can or any other
metal can both as a container
any other metal can
and one of the electrode.
By the end of the lesson, students will be All pairs in class do same
able to
product, then gallery walk to
(A) Work posted by F2.1
pairs for gallery walk F2.2
F2.3
LS:
F2.4
C (working with F2.5
partner
and F3.2

13
Corrosion
12
Know how to use a technological
problem-solving
(trial-and-error)
approach to construct a working
electric cell with the highest possible
voltage.
see if there are differences— constructively
or errors! Repeat with 1 or 2 critiquing work
more
products.
(not other pairs)
procedure…just
choosing
starting
substances
and
writing the word equations
and balanced redox equations)
Students will watch video on
of corrosion
(http://www.youtube.com/wat
ch?v=-oAdk038mIQ)
Teacher will pause the video
before showing the final
At the end of the lesson, students will be results in the three test tubes
able to
and lead to whole class
discussion to predict in which
 Define corrosion
 Explain corrosion in terms of test tube corrosion occurs.
electrochemical process
 Enlist factors affecting the rate of Lecture
corrosion
 Describe
corrosion
inhibiting Teacher will show videos to
students
on
corrosion
techniques
inhibiting techniques so that
they can understand the
techniques in more effective
manner
(http://www.youtube.com/wat
ch?feature=endscreen&v=XB
cEORZOREc&NR=1)
(http://www.youtube.com/wat
Corrosion particular rusting of iron
Factors accelerating the rate
corrosion
Methods of prevention
of A1.2
A1.4
A1.5
A1.6
A1.8
A1.11
A1.12
A1.13
(A)
Students’ F3.6
responses
on
questions related to
videos and during
lecture
A1.1
A1.8
A1.12
LS:
I (to answer
teacher ’s questions)
ch?v=khGuPU8zYTE)
Reading text from Nelson
Chemistry 12 University
Preparation textbook (pg 710714, Year 2003)
Story so far!!
14
Review on Redox reactions and
Electrochemistry
(No new learning goals; consolidating and
strengthening previous concepts)
Whole-class discussion on
problems and doubts
Chalk board Quiz and Self
quiz and Review -Nelson
Chemistry 12 University
Preparation textbook (pg 725727, Year 2003)
Work time: Students may
choose to review individually,
in pairs or in small groups
Culminating
Activity
13
15,
16
Summative; no new learning goals.
(A) Monitor
questions students
ask during classroom
discussion and Chalk
board quiz
(A) Students do selfquiz and review
section of text (p.
725-727); assess
questions asked by
students as they work
LS:
IW (use of review
time)
C (depending on
student’s choice of
grouping)
SR (student seeks
clarification as
needed and
perseveres instead of
giving up)
(E)
Culminating
activity
F2.1
F2.3
F2.6
F3.1
F3.3
Unit Test
17
Summative; no new learning goals.
LS:
IW, R
(E) Unit Test
.
LS:
R and SR (during
test)
Accommodations for ELL:





By having access to computers and internet, students will have access to different translational services (e.g. Google Translate)
and explanatory dictionaries (e.g. Wiki) which will help them understand asked requirements.
A Teacher Assistant (if available), might be invited to help with the activities and text.
Arranging groups in such a way that ELL students can be together with English proficient student, who can speak their
language too.
Translating or illustrating Lab safety instructions (and operating instructions for apparatuses and reagents) with little amount of
writing.
Simplifying the language of procedural writing and handouts.
Special needs student accommodations



14
An educator or Teacher Assistant (if available) who have knowledge and / or experience in dealing with special needs students
might be invited to help in the activity.
As much as possible, creating groups such that all members feel comfortable with each other.
Illustrating lab safety with little amount of writing and more pictures.


Providing additional time
Simplifying the language of procedural writing
Resources

http://www.youtube.com/watch?v=a6RR4kPsnlE
 http://exchange.smarttech.com/details.html?id=2d03db06-a962-49a5-a3e6-6b6885629699
 http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/redox/home.html

http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/electroChem/voltaicCell20.html





http://www.youtube.com/watch?v=oy8dzOB-Ykg









15
http://www.youtube.com/watch?v=-oAdk038mIQ
http://www.youtube.com/watch?feature=endscreen&v=XBcEORZOREc&NR=1
http://www.youtube.com/watch?v=khGuPU8zYTE
http://www.saskschools.ca
Nelson Chemistry 12 University Preparation textbook (Unit 5, Chapter9, Year 2003)
Practice sheet1
Practice sheet 2
Practice sheet3
Practice sheet4
Every Pupil response
Assignment sheet 1
Assignment sheet 2
Assignment sheet 3
EVERY PUPIL RESPONSE
1. Hydrogen has oxidation potentials of 0.
2. What does the standard reduction potential measure
3. The standard oxidation potential is not much like the standard reduction potential.
4. The standard reduction cell potential and the standard oxidation cell potential can never be combined.
5. What conditions must be met for a potential to be standard?
6. Based on the activity series, which species will be oxidized and reduced: Zn2+ or H+.
7. The standard reduction potential of Fe3+ is +0.77V. What is its standard oxidation potential?
Pink Card
Yellow Card
1. True
False
2. The tendency for a given chemical species to be
reduced.
The tendencies for a given chemical species to
be oxidized.
3. True
False
4. True
False
5. T=298K, P=1 atm, M=1M
T=398K, P=2atm, any conc. of solution
16
6. H+ is reduced while Zn2+ is oxidized.
Zn2+ is reduced while H+ is oxidized.
7. -0.77V
+0.77V
17
Electrochemistry
Practice Sheet 1: Oxidation Numbers and Redox Reactions
1. Determine the oxidation number of each element in the following compounds.
Rules: 1. Pure elements have an oxidation number of 0
2. If the compound is an ionic compound, the oxidation number for
each element is the ion’s charge
3. The oxidation number of hydrogen in a compound is +1
4. The oxidation number of oxygen in most compounds is –2
(peroxides are the exception; in peroxides oxygen has an oxidation
number of –1)
5. The sum of the oxidation numbers in a compound is zero.
6. The sum of the oxidation numbers in a polyatomic ion is equal to
the ion charge.
Hint
Oxidation Numbers for each Element
SnCl4
Rule 2
Sn
Cl
b. Ca3P2
Rule 2
Ca
P
a.
18
c.
SnO
Rules 4, 5
Sn
O
d. Ag2S
Rule 2
A
g
S
e.
HI
Rule 3, 5
H
I
f.
N2H4
Rule 3, 5
N
H
g. Al2O3
Rule 4, 5
Al
O
h. S8
Rule 1
S
i.
HNO2
Rules 3, 4, H
5
j.
O2
Rule 1
k. H3O+
O
O
Rules 3, 4, H
6
O
ClO3-
Rules 4, 6
Cl
O
m S2O32.
Rules 4, 6
S
O
n. KMnO4
Rules 4, 5, K
6
l.
19
N
Mn
O
o. (NH4)2SO4 Rules 4, 5, N
6
H
S
O
2. Determine the oxidation number of carbon in each of the following compounds:
a. methane, CH4
c. carbon monoxide, CO
20
b. formaldehyde, CH2O
d.
carbon dioxide, CO2
Electrochemistry
Practice Sheet 2: Recognizing Redox Reactions
1.
For each of the following reactions, complete the summary table below the equation. If an element does not undergo any change,
leave the last two columns blank
a. 4 HCl + O2  2 H2O + 2 Cl2
element
Initial
Final
Ox. No
Ox. No.
H

Cl

O

b. 4 Al(s) + 3 O2(g)  2 Al2O3
21
egained
or lost
Oxidized or
reduced
Agent
element
Initial
Final
Ox. No
Ox. No.
Al

O

egained
or lost
Oxidized or
reduced
Agent
Oxidized or
reduced
Agent
c. Fe(s) + SnCl2(aq)  FeCl2(aq) + Sn(s)
element
22
Initial
Final
Ox. No
Ox. No.
Fe

Sn

Cl

egained
or lost
Electrochemistry
Practice Sheet 3: Balance Redox Reactions Using Oxidation Number Method
Balance the following redox reactions using the oxidation number method.
a. SnCl2 + HgCl2 → SnCl4 + HgCl
balance for electrons
initial
final
change
Total
e-
Coefficient
Sn
→
×
=
Hg
→
×
=
Answer:
b. HNO3 + H2S → NO + S + H2O
balance for electrons
initial
N
23
final
→
change
Coefficient
×
Total e=
S
→
×
=
Answer:
c. NaClO + H2S → NaCl + H2SO4
balance for electrons
initial
final
change
Total
e-
Coefficient
Cl
→
×
=
S
→
×
=
Answer:
d. CdS + I2 + HCl → CdCl2 + HI + S
Because one of the atoms undergoing oxidation or reduction has a subscript (I2) we will account for the number of atoms of
each element when preparing our summary chart:
balance for electrons
24
initial
S
→
I
→
Answer:
25
final
no.
atoms
change
×
(in I2)
No.
e-
=
Total
e-
Coefficient
×
=
×
=
Electrochemistry
Practice Sheet 4: Balance of Redox Reactions
1. Balance the following half-reactions for both atoms and electrons by adding the appropriate number of electrons to the
correct side of the equation. Also identify each as either an oxidation or reduction.
Oxidation
or
Reduction?
Add electrons to the equation
a.
Pb2+ → Pb
b.
Cl2 → Cl-
c.
Fe3+ → Fe2+
d.
N2O + H2O → NO + H+
2. Break each equation into two half-reactions. Identify each half-reaction as oxidation or reduction.
a.
Cu + 2 H+ → Cu2+ + H2
oxidation
reduction
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b.
2 Al + 3 S → Al2S3
oxidation
reduction
3. Balance the following equation using the half-reaction method.
a. Na + Br2 → NaBr
Step 1
Write the two balanced
half-reactions, removing
any spectator ions:
add together:
reform compound:
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Step 2
Step 3
Balance for electrons
Add the half-reactions,
replacing any spectator
ions that were removed
and/or recombining
compounds
Assignment Sheet 1
Redox Reaction and Electrochemistry
(Oxidation Number)
1. Define oxidation and reduction.
2. Determine the oxidation number of nitrogen in each of the following compounds:
a.
NH3
b.
NO2
c.
Ca3N2
d.
NI3
3. Determine the oxidation numbers of the requested element in the following compounds:
a.
S in SO2
b.
Mn in MnO2
c.
Cr in Cr3+
d.
S in SO42-
e.
B in H3BO3
f.
O in Na2O2 (hint: this is a peroxide)
4. Determine the oxidation of each element in (NH4)2CO3
5. The following reactions are not complete reactions. Determine if each of the following changes is an oxidation, a reduction,
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or neither:
a.
SO32- → SO42-
b.
CaO → Ca
c.
CrO42- → Cr2O72-
d.
2 I- → I2
6. For each of the following reactions, complete the summary table below the equation. If an element does not undergo any
change, leave the last two columns blank. Also provide the formula of the oxidizing or reducing agent. An example is
shown.
a.
b.
CuO + H2 → Cu + H2O
element
Initial
Ox. No
Cu
+2
O
→
H
→
egained or
lost
Oxidized or
reduced
Oxidizing or
Reducing Agent
0
gain 2
reduced
oxidizing agent - CuO
egained
or lost
Oxidized or
reduced
CH4 + 2 O2 → CO2 + 2 H2O
element
C
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→
Final
Ox. No.
Initial
Ox. No
Final
Ox. No.
→
Agent
H
→
O
→
7. Not all of the following reactions are redox reactions. Place a check mark in the appropriate column for each reaction.
Redox
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a.
Na2S + FeCl2 → 2 NaCl + FeS
b.
2 Na + 2 H2O → 2 NaOH + H2
c.
2 KClO3 → 2 KCl + 3 O2
d.
SO2 + H2O → H2SO3
e.
2 Al + 6 HCl → 2 AlCl3 + 3 H2
Not Redox
Assignment Sheet 2
Redox Reaction and Electrochemistry
(Balance Redox Reactions)
1.
2.
3.
4.
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Balance the following reactions using the oxidation number method.
a.
NaClO + H2S → NaCl + H2SO4
b.
Sn + HNO3 + H2O → H2SnO3 + NO
c.
K2Cr2O7 + SnCl2 + HCl → CrCl3 + SnCl4 + KCl + H2O
Balance the following half-reactions. Be sure to balance for atoms first, then balance for charge by adding electrons to the
appropriate side of the equation. Also identify each as either an oxidation or reduction.
a.
Br2 → Br-
b.
Fe2+ → Fe3+
c.
MnO4- + H+ → Mn2+ + H2O
Break each equation into two half-reactions. Identify each half-reaction as oxidation or reduction.
a.
2 K + I2 → 2 KI
b.
2 Br- + F2 → Br2 + 2 F-
Balance the following reactions using the half-reaction method.
a.
Na + Br2 → NaBr
b.
CrO42- + H+ + Cl- → Cr3+ + Cl2 + H2O
Remember to balance for atoms before adding electrons to balance for charge!
5.
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Balance the following reactions using either the oxidation number method or the half-reaction method.
a.
NO + As + H2O → N2O + HAsO2
b.
Ce4+ + I- + OH- → Ce3+ + IO3- + H2O
Assignment Sheet 3
Redox Reactions and Electrochemistry
Standard Cell and Cell Potential
For questions 1 to 3, two half-cells are connected under standard conditions to make an electrochemical cell.
For each:
a. Write the equation for each half-reaction that will occur
b. Label each half-reaction as oxidation or reduction
c. Calculate the voltage of the electrochemical cell
d. The net overall balanced redox equation.
e. Diagram the cell, clearly indicating the following






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the electrodes in appropriate electrolytic solutions
label each electrode as anode or cathode
label each electrode as positive post or negative post
diagram the flow of electrons through the external circuit
a salt bridge with appropriate electrolytic solution
flow of ions from the salt bridge to the two half-cells
STANDARD REDUCTION POTENTIALS FOR HALF-REACTIONS
Ionic concentrations are a 1 M in water at 25C
Half-reaction
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E (Volts)
Au3+ + 3e-  Au(s) .............................................................
+1.50
Cu+ + e-  Cu(s) ...................................................................
+0.52
Pb2+ + 2e-  Pb(s) .............................................................
-0.13
Fe2+ + 2e-  Fe(s) ..............................................................
-0.44
Cr3+ + 3e-  Cr(s) ...............................................................
-0.74
Al3+ + 3e-  Al(s) ................................................................
-1.66
Mg2+ + 2e-  Mg(s) ...........................................................
-2.37
Rb+ + e-  Rb(s) ...................................................................
-2.98
1. iron-iron(II) ion (Fe|Fe2+) and lead-lead(II) ion (Pb|Pb2+)
2. chromium-chromium(III) ion (Cr|Cr3+) and rubidium-rubidium ion (Rb|Rb+)
3. copper-copper(I) ion (Cu|Cu+) and aluminum-aluminum ion (Al|Al3+)
4. An electrochemical cell is created using gold and magnesium half-cells. Determine which half-cell will
undergo oxidation and which will undergo reduction, identify anode and cathode, and calculate they
voltage for the cell. You do not need to diagram the cell.
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