GET A JOB... BUILD A BATTERY!
Grades 5-12

In this lesson students design and construct a battery (electrochemical cell). They become very interested in this project and the rather sophisticated theory behind it after being presented with a letter offering them a high paying job to design a battery. The interest is heightened and understanding is enhanced by viewing a video on batteries dealing with theory and practical applications. The student works in a team to design and construct a working battery (cell) and is responsible for a labeled diagram of its operation. There is a little competitive fun involved and the level of sophistication can be adjusted to a wide range of student ability and age.

World of Chemistry: The Busy Electron (The Annenberg/CPB Collection )

Students will be able to:

• design a battery (electrochemical cell);
• identify and label the anode, cathode, electron flow, ion flow, oxidation and reduction reactions, chemicals used including the location of each;
• distinguish between anode materials with regard to energy potential;
• calculate the theoretical voltage from a chart; and
• construct a working battery.

• large voltmeter with wires and alligator clips at front of room for class use, periodic charts, standard reduction potential charts (E°) and per group of two or three high school chemistry students:
  • a U-tube
  • glass wool
  • two beakers
  • distilled water
  • pure copper sulfate
  • pure magnesium sulfate
  • pure aluminum sulfate
  • pure sodium chloride
  • pure magnesium
  • pure aluminum
  • pure copper
  • pure zinc

OR
per group of two or three grade 4-9 students:

• one lemon
• iron nail 2-3 inches
• at least two other metals about the size of the nail such as:
  • aluminum foil or strip of flashing
  • magnesium ribbon
  • zinc strip or galvanized metal sheet
  • copper wire

Begin the lesson by showing some interesting battery device (I usually dress up as "Dan The Battery Man" with a flashing head band and carrying a cutaway auto battery) to raise curiosity about what a battery is and what makes it work.

In a high school chemistry class the students would have already done some reading about the periodic table, metals, non-metals, atoms, ions, gain and loss of electrons, but this is not essential. You might mention that metals are generally located on the left side of the periodic table and tend to lose electrons. It is important that students understand that an anode is where electrons come from and a cathode is where electrons go, and that an electrolyte is a solution containing ions. How much of the background material you have the students deal with in advance of this lesson depends on to what extent you wish to make this lesson "discovery" versus "illustrative."

After asking students what they think makes a battery work, I would give them a copy the activity (this is usually in the form of a letter from a fictitious company stating the problem and materials available for their use (see attachment) and a blank sheet of paper for notes and ideas. They would then be told to read the letter and to jot down at least one idea and one question regarding the battery mentioned in the letter. Have a few students read what they wrote and assign students to teams of two to four students to share their ideas and questions for two minutes. Inform them that they are about to see a rather interesting video about batteries, and that some of their questions may be answered before it is over so they may move to discuss with team-mate(s), but be in position to watch the monitor.

The focus for viewing is a specific responsibility or task(s) students are responsible for during or after watching the video to focus and engage students' viewing attention. After watching this video students should be able design and label "battery" as called for in the activity letter. To give students a specific responsibility while viewing, the Focus For Viewing Notes (see attachment) should be distributed after the second pause in viewing in order to respond in writing to the teacher's questions and to jot down notes and ideas during video.

BEGIN the video The Busy Electron at approximately six minutes into the program where the rusting boat is shown in the water. In order to heighten curiosity and sharpen focus, do not use sound. PAUSE after about 25 sec. as soon as the magnesium burns. Ask the class whether anyone can identify what they saw and what it might have to do with electricity. REWIND to the same starting point. REPLAY with sound for about 1.3 min. to the explanation of the copper-zinc reaction where positive copper ions are shown to gain electrons and narrator says, "Copper ions gain two electrons...they're reduced to copper atoms." PAUSE. Ask the class, "What is meant by oxidation and reduction?" Distribute the Focus For Viewing reprint. REWIND the explanation (10 sec.). REPLAY. PAUSE at end of explanation again. Direct each student to write the meaning of oxidation and reduction on the focus reprint.

RESUME the video for about 2.25 min. PAUSE after the demonstrator shows the zinc-copper cell and says, "There's the electric current!" Now ask students if they know what oxidation has to do with a battery. Spend no more than a minute discussing these questions at this time, but tell them more hints are coming.

Ask students if they know how current is produced and where the electrons go. RESUME the video for about 50 sec. PAUSE after the narrator says, "Here positive copper ions combine with electrons from the zinc to form copper atoms." Ask students if they now know where the electrons go (thru the wire) and what caused the current [loss of electrons by zinc - oxidation and gain by copper - reduction). After a few responses, ask them to write notes on the focus reprint.
Have them "caucus" with their team-mates for two minutes or so to decide how they might use some of the materials listed in the letter to construct a battery. Each student should make a labelled rough sketch on blank paper as a result of this discussion. (It is very difficult for some students to come up with ideas on their own. They may be very dependent on teacher directions. After a few "real" experiments such as this, they become more independent, so be stingy with hints.)

Ask students if they understand how ions move and why the electrons go from the zinc to the copper. RESUME the video for about one min. PAUSE after the commercials say, "No battery lasts longer...the new energizer!" Ask them if they now know why ions move (keep charges balanced or equal everywhere) and if they know why the electrons go from zinc to copper (zinc gives up electrons more readily than copper). Have them make notes on their paper and limit discussion at this time to one minute.

Ask students to focus next on these questions: "What is a lithium battery?, Is lithium the anode or cathode?, Why is lithium desirable?, What is the function of the electrolyte?" FAST FORWARD for about three min. to the end of the pacemaker segment where the narrator says, "From the Greatbatch origins, new applications of the lithium battery have expanded..." RESUME the video for about two min. PAUSE at the moment the antique autos come on. Question students about the function of lithium in this battery. (Lithium is the anode and is desirable because it is light and very reactive.) Ask students about the function of the electrolyte (to allow ions to flow and maintain charge balance) and to respond to the last few questions on the focus reprint.

Instruct students to get together with teammates and decide on a design for a battery based on what they learned from the video. Remind students that they are limited to the materials listed in the letter and are striving for maximum energy (volts). Each student should make the labeled sketch called for in the letter before actually constructing a battery. The sketch will not be the final drawing, just a rough draft to encourage thinking and planning.

Point out that the E° chart will allow experimenters to predict in advance the voltage produced by oxidizing and reducing chemicals by adding the oxidation potential to the reduction potential when the solutions used are 1.0M. For advanced students familiar with logarithms, the Nernst equation "E = E° - (0.0257/n)lnQ" can be used to calculate the voltage at various concentrations. This can be done before the experiment to illustrate the theory or can be done after the experiment to make the experiment more interesting and create the "aha" after students have worked on the problem first.

Note to the teacher: This experiment can get messy, but high school students familiar with standard lab and safety procedures usually find this the most interesting, educational, and fun experiment of the year. I usually have either an applause tape or theCelebrate tape by Cool And The Gang go on when they get a battery to work. The whole project can be done in a typical double lab block or done over two days. The chemicals are relatively cheap and need not be of highest purity. A paper towel wet with electrolyte can be substituted for the U-tube but is less reliable. The towel or glass wool must be thoroughly wet to work. The copper sulfate is toxic and harmful to eyes so goggles are a must.

For younger students this activity can be done with a citrus fruit providing acidic hydrogen ions for reduction and ions throughout, so one fruit with two metals stuck in it will work! Some of the theory and video segments can be left out.

A large demonstration voltmeter or galvanometer is ideal, but any voltmeter or ammeter will work if it is sensitive enough for your choice of chemicals. Do test it in advance!

Show a cutaway auto battery and discuss the function of the lead anode, the acid cathodic reaction and the multiple cell construction.

View the section of the Busy Electron video on the auto battery (16 min. into video) and raise questions as to what the anode is and how is it recharged.

Have students write to commercial battery companies (Duracell, Eveready, Ray-o-vac, Kodak) to find out what anodes and cathodes work best for different purposes.

Construct a battery of cells from magnesium and battery acid (sulfuric) to light a light bulb.

Experiment with iron and aluminum nails in water and in various solutions to illustrate less useful forms of oxidation.

Call or visit some auto parts dealers to find out stats on auto batteries and why they vary.

Have students do internet or library research on design of commercial batteries as part of a lab report or as a bonus.

Suggest that students might contact a large hospital to find out information on heat pacemaker batteries or obtain contacts from the hospital to pursue this. They might be stimulated after viewing the pacemaker section of the Busy Electron video (12 min. into video).

Math and Science: Suggest an interdisciplinary extra-credit project where students graph voltage and time for different brands of batteries or for different types. A cost analysis might be done in conjunction with this.

Math and Science: Design an experiment where the components of a battery remain constant but the concentration of the solutions vary. Construct graphs showing the voltage vs. concentration of each solution.

Technology and Social Studies: Have students call or write major auto manufacturers to find out the latest developments in battery-powered cars.

Social Studies and Science: Have students research the history of the battery.

Social Studies and Health: Have students call or write the E.P.A. to find out the environmental hazards of battery disposal.

Health: Have students write to a commercial battery company or O.S.H.A. to learn about the potential of an explosion in recharging an auto battery.

Master Teacher: Raymond Suzor

Click here to view the worksheet associated with this lesson.