Electrochemistry Unit
By John H. Fisher
Course
General Chemistry (Chem 101 – IAI)
Physical Science (Phys 101)
These modules will have application and transfer possibilities to any other chemistry,
physics, electronics, or general science courses that include an introduction to
electrochemical cells.
Note: One of the applications will also have interdisciplinary relationships to art
(specifically jewelry making).
Description
This set of 14 chemistry lecture/laboratory computer-related modular exercises is
designed to be used with an interactive teaching unit (approximately two weeks in
duration) dealing with electrochemistry. The content covered in this unit will include the
majority of the topics listed on the concept map below:
The modules are designed around the learning cycle concept, and when appropriate, they
have been aligned with the ISBE Learning Standards (Goals 11-13); National Science
Education Standards; ACS Voluntary Industry Standards; and Work Keys. Attempts have
also been made to give the modules an interdisciplinary or industrial application when
possible. Each module also has the ability to be “scaled up” or “scaled down” so as to be
made useful for advanced community college courses and also appealing to our
colleagues at the elementary and secondary levels.
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The modules have been developed with varying degrees of technological infusion, which
this writer has found greatly enhances student understanding and enjoyment. The
technologies employed range from useful Internet links and websites, digital camera and
PowerPoint applications, to interactive software, demos, and computer interface units for
data collection and analysis. It will be obvious that some of the lessons can be
accomplished via traditional pedagogy without the technological inclusions, while other
module sets can only be accomplished via the applied technologies.
Faculty Technology Skill
Faculty should have basic computer skills such as using a web browser to navigate the
Internet, downloading and extracting files, installing plug-ins and CD-ROMs, using
PowerPoint, and perhaps some “smart classroom” experience.
Student Technology Skill
Students should have basic computer skills sufficient to access and use pre-installed
software once the methods for this are explained. They should know how to use a
browser to explore the Internet and possess the ability to download files and cut-pasteprint.
Faculty Equipment
• Computer with Internet access and CD-ROM drive
• Access to “smart classroom” technology if the modules are to be used solely as a
lecture presentation.
• Falcon Software, Inc.’s Exploring Chemistry CD-ROM
• W.H. Freeman’s Bridging to the Lab CD-ROM
• McGraw/Hill e-text for Chemistry 7th Edition by Chang.
Note: Most modern chemistry textbooks offer an accompanying CD-ROM. This may
easily be substituted for Chang’s e-text.
Student Equipment
Students should have access to a computer with Internet connections. The computer
should have a CD-ROM drive, or the technologies may be downloaded to a file server on
a network.
Cost
This section assumes that appropriate hardware such as computers, printers, and smart
classrooms exist at the institutions. If this assumption is accurate, then the cost estimates
may be categorized as follows:
•
Websites, e-mail sites, and the downloadable pictures suggested are free.
•
Chang’s e-text or comparable software for specific text being used usually comes
bundled with the textbook at no additional cost to the instructor or the student.
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•
The Bridging to the Lab CD-ROM and accompanying laboratory workbook from W.
H. Freeman is $15.00. I am considering this to be a student lab manual expense. This
is an outstanding interactive CD and accompanying website with which I am very
impressed.
•
The Exploring Chemistry CD-ROM from Falcon Software, Inc., is the most
expensive technology tool employed. Instructors may purchase a site license for the
multi-user version of the CD and its accompanying classroom management package
for $1,795 to $3,695. A license for the single station CD may be purchased for $495
to $695. A third option involves having students buy access to the web version My
Chem Class at $30 per student. This is a 12-month subscription that is accompanied
by an excellent e-text and nicely replaces the traditional lab book especially when
supplemented with instructor-generated laboratory experiment scenarios.
Improvements on Teaching and Learning
When I first began teaching science at the college level in 1982, I defined the challenge I
faced as an instructor as follows: “How do I prepare science students for a technology
driven world that is changing more rapidly than at any time in history?” Now some 20
years later, I realize my challenge is still the same. The answer seems to be to explore
every new technology tool and extract the best that each has to offer, then combine those
extractions into teaching units that inspire both teacher and student. I feel that this revised
electrochemistry unit does this. The technologies employed take the student beyond the
confines of the classroom into a challenging virtual world of “real-life” applications of
academic chemical theory. The websites visited give clear, consise tutorial information
and diagrams. The interactive CD-ROM material is outstanding in that the exercises are
repeatable, and they are success driven. (Experimental choices must be correct, or
corrected, before the student may move to the next section.) This repeatability of the
exercises in a short span of time at no cost and with no waste is invaluable and far
superior to traditional methods. The practice questions and challenges throughout the
program reinforce the content and better prepare the students for their final laboratory
challenges.
Nontechnology Comparison
I firmly believe that combining modern technology with traditional classroom pedagogy
is far superior to the lecture/textbook approach or I would not be involved with this
project.
Could a student achieve the same level of understanding using the traditional format?
Certainly. However, I don’t think it could be done in as short a time span, or as
inexpensively and as interestingly.
Pertinent Issues
The classroom instructor is still, and always will be, the best tool for students to use as
they learn chemistry. Technology can greatly help us to visualize science in a virtual,
interactive world as never before possible, before this exciting visualization can occur,
the student must have a strong foundation for these new ideas, and this foundation must
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come from the classroom instructor. The classroom instructor is indispensable and must
always be available for instruction, guidance, and help with the technology.
How to Use This in the Classroom
You will note that the modules (i.e., computer technology applications) are presented as
support and instructional components of a unit on electrochemistry. The unit as presented
is incomplete. I would want to add topics on the following for my complete unit:
rechargeable batteries, lead storage batteries, the Down’s cell, corrosion protection, and
fuel cells (both H2/O2 and biochemical). I believe that the experiences are most profitable
as interactive, hands-on, student-driven exercises; however, they are designed so that they
could also be used as lecture demonstrations in a smart classroom setting. Done this way,
they should be accompanied by Socratic question-and-answer dialogue between the class
and the instructor.
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Electrochemistry
(Galvanic and Electrolytic Cells)
I.
Goals and Objectives
II. Introduction
Electrochemistry is the branch of chemistry that deals with the relationships
involved in the interconversion of chemical and electrical energy. Electrochemical
cells are involved in these procedures. Electrochemical processes are oxidationreduction processes in which one of the following occurs:
•
Energy from a spontaneous chemical reaction is converted to electricity.
(Voltaic-Galvanic cell)
•
Electrical energy is used to cause a nonspontaneous reaction to occur.
(Electrolyte cell)
At this point, I would distribute a list of study goals for the unit, a list of definitions
of important terms, and a concept map. Both of these lists are available upon request.
Then, I would move into the exploration phase of the unit.
III. Exploration
It should be noted that I usually have students work in lab groups of two to four
during this phase, and since this unit takes place late in the semester, they are given
advanced notice to have their safety goggles with them for both lecture and lab.
A. Voltaic or Galvanic Cells
1. Distribute Material
a. Batteries (AAA – D)
b. Flashlight bulbs (AAA – D)
c. Wire (Cu, al, etc. etc.)
2. Explore ways to make the bulbs light.
3. Record your explorations, observations, in your “Lab Journal.”
4. Make some preliminary predictions.
B. Electrolytic Cells
1. Distribute Materials
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a. 9-volt lantern battery
b. Wires of various metals
c. Metal objects (e.g., paper clips)
d. Nonmetal materials (e.g., plastic or rubber coated paper clips)
e. A dilute aqueous solution of an electrolyte (Copper II Sulphate – CuSo4
works very well)
2. Explore ways to try to “coat” or “plate” the paper clips.
3. Record your exploration and observations in your “Lab Journal.”
4. Make some preliminary predictions.
IV. Lecture, Discussion & Direction Pertaining to Exploration Phase III
A. Galvanic Cells
1. Review definitions of galvanic cells.
2. Have students download the cross section of a battery from the Usborne
Library of Science Internet site at www.usborne-quicklinks (Light, Sound and
Electricity, page 57). Once downloaded, have students label the parts using
the references in Chang’s Chemistry, chapter 19.
3. Direct students to topic “Batteries,” Lesson #1, “Voltaic Cells” on the
Exploring Chemistry CD-ROM from Falcon Software, Inc.
4. View the “mini movie” on Chang’s CD.
5. After viewing the interactive lesson on batteries, ask students to build a cell
from the following:
(5 points each)
a. A lemon, Cu wire, Zn wire, and a voltmeter.
b. Ten penny-sized discs of Al (Reynold’s Wrap), ten penny-sized discs of
filter paper soaked in lemon juice of NaCl (aq) (saltwater) or vinegar and a
flashlight bulb.
6. Cornwall’s site.
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7. Students will design cells from the following:
(5 points each)
a. Aluminum wire, aluminum3+ solution, copper wire, copper2+ solution,
voltmeter
b. Series and parallel circuits using Al foil, Cu wire strands, alligator clips, a
solution of lemon juice or saltwater or vinegar, and flashlight bulbs.
8. Ask students to predict whether they can make a working cell from two
people, Zn and Cu wire, and a voltmeter.
9. Have students design and implement their people battery.
(5 points)
10. Direct students to the Exploring Chemistry CD-ROM, Topic K, “Batteries,”
Lesson #2: Nernst Equation.
11. Direct students to the Bridging to the Lab CD-ROM selecting
“Electrochemistry: Using the Nernst Equation.”
B. Electrolytic Cells
1. Review definitions of electrolytic cells.
2. Direct students to download the picture from page 33, Usborne Internet
Linked Library of Science: Mixtures & Compounds, and label it from
diagrams in the text.
3. Assist students with the understanding of the downloaded diagrams.
4. Direct students to the following websites:
a. www.finishing.com/faqs/howworks.html
b. Awards and recognition website (Oscar plating)
c. www.artisanplating.com/articles/articles.html
5. Demo H2O electrolysis, explaining more bubbles (H2) at cathode.
6. Have students design a system for plating base metal. Provide 6V lantern
battery, Cu wire, and CuS04 solution.
(10 points)
V. Authentic Curriculum Scenario
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Since all experts on curriculum design and learning/teaching styles agree that the final
phase in authentic curriculum development is to have the students apply the concepts
of the unit to a design of their own, I give them the following scenarios as one of their
assessment projects:
“One of your fellow lab mates tells you that the hospital where his father is
administrator has several obsolete items that they wish disposed of. Among these is a
large quantity of old x-ray negatives. He reminds you that the older the film, the
greater the concentration of silver in the negative. Since you can obtain the negatives
for almost nothing you decide to form a partnership.”
Design a process involving redox and electrochemical cells that might allow you to
reclaim the silver from the negatives. Be as specific as possible in your descriptions
of the electrorefining unit you develop. Include all appropriate calculations,
equations, and chronology.
You will be assessed as follows:
A. Scientific Method: Hypothetical Statement
15 points
B. Procedure
1. Treatment procedure for original film, making it ready
for electrochemical treatment
10 points
2. Application of Nernst equation to calculate silver concentration
in material from A-1 above
10 points
3. Use of Galvanic and electrolytic cells in obtaining the silver
10 points
4. Schematic design with labels
10 points
C. Application and Implementation
1. Run the experiment.
15 points
D. Communication
1. Present data in both spreadsheet and graph formats.
15 points
2. Analyze data and relate to hypothetical statement.
15 points
VI. Complete Electrochemistry Unit
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The unit as presented is incomplete. I would want to add topics on the following for
my complete unit: rechargeable batteries, lead storage batteries, the Down’s cell,
corrosion protection, and fuel cells (both hydrogen/oxygen and biochemical).
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