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Highlights
SUSAN H. HIXSON
National Sctence Foundation Arlington,VA 22230 CURTIS T. SEARS, JR. Georgia State University Atlanta, GA 30303 -
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Projects supported by the NSF Division of ~ n d e r ~ r a d u aCducation te An Interactive Multimedia Software Program for Exploring Electrochemical Cells Thomas J. Greenbowe Iowa State Jn Yerslly of Sc~enceand Techno ogy Arnes, IA 50011
Many chemical processes are difficultto communicate effectively because the concepts require individuals to visualize the movement ofmolecules, ions, or electrons. Herron and Greenbowe (1)have stressed the importance of instructors helping students make connections between three levels of representation: macroscopic, microscopic, and symbolic. Static diagrams, graphs, chemical equations, mathematical equations. and chemical symbols are part of the symbolic ievel of representation. ?:hemistry demonstrations and laboratory actirities idlow students to directly observe chemical reactions a t the macroscopic level. Amissina component of instruction is a way to convey the m i c r ~ ~level ~ i cof representation of a ihemical process. Explaining dynamic processes of equilibrium reactions and-oxidation&ductibn reactions becomes easier when students can observe a computer animation or simulation of these processes. McPhillen and Greenbowe (2),Lynch and Greenbowe (31, and Greenbowe and Parker (4) have developed computer animated sequences and interactive multimedia instructional programs for use in introductory chemistry. The "Electrochemical Cells Workbench" is one component of a software package that allows students and faculty to explore building and testing electrochemical cells. The "workbench" is a microworld environment simulating a chemistry laboratory in which a student can perform experiments. The "workbench" section of the program provides students and instructors the opportunity to manipu-
Figure 2. A computer screen image of the electrochemistry workbench showing a voltmeter, metal electrodes, wires, and saltbridge. late experimental apparatus, chemicals, and instruments in order to design and build an experiment. Students use a mouse to "point-and-drag"objects on the screen that represent beakers, various metal electrodes, salt bridge, wires, and a voltmeter to seeup and test a n electrochemical cell. For example, when viewing the screen the student selects three solutions to work with from a menu of 12 solutions. The solutions appear as labeled reagent hottles on a shelf. Beakers are moved under the spigots of each bottle. The spigot from a bottle is opened to allow the solution to fill one of the beakers. Figure 1 shows a computer screen of the chemistry workbench with three 1.0 M aqueous solutions to choose from. In this example, the student is choosing to work with aqueous 1.0 M coppedII) nitrate in one beaker and aqueous 1.0 M zinc nitrate in another beaker. The menu of aqueous solutions also includes the option of working with 0.10 M, 0.010 M, and 0.0010 M aqueous solutions. enabline students to exolore concentration cells equation. Next, the and calklations i&olviug the student selects metal electrodes to lace in the solutions. A menu presents various metal electiodes to choose from. If a student wants to explore building an electrochemicalcell by placing a zinc metal electrode in copper(I1) nitrate solution and by placing a copper electrode in zinc nitrate solution, the program will do so. This is an important component of interactive multimedia: the user is presented with decisions to make just as if he or she were in a laboratory working with electrochemical cells. The program prompts students with hints if they are having trouble setting-up a cell, and there is a help menu also. Figure 2 shows the components of an electrochemical cell being assembled. One beaker contains 1.0 M coppedII) nitrate and a copper electrode; a second beaker contains zinc nitrate and a zinc electrode. Avoltmeter, wires, and a salt bridge are available. The student moves the wires to connect the electrodes to the voltmeter. Again, the student must make a decision: which electrodes should be connected to which terminals.
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Figure 1. A computer screen image of the electrochemistry workbench showing three aqueous solutions and two beakers.
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Figure 3. Acomputer screen image of a copperlzinccell with a digital color overlay (right).
Figure 5. Acomputer screen image of acopperlzincelectrochemical cell with zoom, click-touch areas.
A salt-bridge must be inserted connecting the two beakers in order to complete the circuit. If students connect the wires one way and obtain a negative voltaze on the voltmeter, they can readily change the connemions of the wires to obtain a positive voltage. When the elec~rochemicalcell is assembled, a color digital photograph ol'a similar electrochemical cell connected to a voltmeter is displayed alongside the simulated cell as shown in Firmre 3. After assembling a n electrochemical cell, the student has the option of viewing animation sequences on two scales. The first scale shows an animation of the entire electrochemical cell. The student observes simultaneous oxidation-reduction reactions occurring at each electrode, migration of ions in the solutions, migration of ions within the salt-bridge and at the ends of the salt-bridge, and direction of movement of electrons in the wire. This view reinforces the dynamic nature of electrochemistry and provides students with a representation at the microscopic level. Figure 4 shows a computer screen of one frame of an animation for a copper-zinc electrochemical cell. A mouse is used to "click-on" control panel buttons that pause, move ahead one frame a t a time, move backwards one frame at a time, repeat, or exit the animation. The second scale of animation allows users to click-on areas of the cell to observe a "zoom view" at the atom or ion level as shown in Figure 5. Zooming in on the copper electrode shows copper(I1) ions in solution and copper atoms comprising the electrode. As electrons are shunted down
the electrode, copperiII) ions move toward the electrode where they each acquire two electrons. When the electrons 1 ) increases as it are awuired. the size of the c o ~ ~ e r ( Iion becomes a copper atom and atta%est;the electrode. Comuuter animation helus make the connection between the chemical symbols, ci21(aq) + 2 e -> Cub), and the microscopic level of representation of this process. Figure 6 illustrates the reduction process occurring - at the cathode. A small image of the copper-zinc cell appears in the upper right-hand corner with a box around the copper electrode to help students recognize that what they are viewing is the enlarged area around the copper electrode. It also serves to reinforce to students that other processes are happening simultaneously in the cell. While comuuter-animated sequences are fine for simulating dynamic motion of m o l e h e s (microscopic representation), students need to be able to connect these models with actual chemical processes. Used by instructors in their lecture presentations, the animations are most effective when coupled with live demonstrations of electrochemical cells. In the laboratory, students construct several electrochemical cells using metals, solutions, a salt bridge, wires, and a voltmeter. Before they measure the voltage, the students draw a diagram predicting the location of the oxidation and reduction processes, the movement of electrons in the wire, migration of ions within and at the ends of the salt bridge, and the identity of the anode and the cathode. They check their predictions with the
Figure 4. A computer screen image of a copperlzinc electrochemical cell.
Figure 6. Azoomed-in image of a representation of a copper electrode functioning as a cathode.
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Journal of Chemical Education
computer animation. Of particular interest is the discovery by students that a negative voltage does not indicate that the electrons and oxidation-reduction process is reversed. The results of preliminary studies indicate that the program helps students achieve a better conceptual understanding of the processes occurring in electrochemical cells. These studies also indicate that student learning styles play a role in whether or not students benefit from viewing and working with the animations, simulations, and instructional modules. The interactive multimedia program becomes a problem solving tool, a wnceptualizer, and a tutorial for the student.
Acknowledgement The National Science Foundation Division of Undergraduate Education has provided support for this project through Grant No. DUE 9253985. Literature Cited 1. Hermn, J. D.; Greenbowe, T. J. J Cham Edue 1986,63.528. 2. Lynch, M ; Greenbowe,T J. "An InteractiveKineties Program'.Apaper presented at the 12th Biennial Conference on Chemical Education, University ofCalifornia Davis. Davis. CA, Augvrt 6.1992. 3. McPh3len. M. A ; Greenbowe, T. J."An I n t t t a d i ~ eE l ~ t t h h m i i i Cell l Programgra.A paper presented at the 12th Biennial Conference on Chemical Education,University of California-Davis, Davis, CA, Avgvrt 6, 1992. 4. Greenbowe, T J . ; Parlte~M. M. l l s i n g Interactive Multimedia To Help Students understand f i n p l e a and concepts of ~ ~ ~ ~ C ~ tI Y SA~~~~ .~ = presolted h ~ ~ nf the American Chemical Society meetin& San Diego, March, 1994.
Science Education Is Focus of New RCS Prosram -
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The recently reestablished State and Lacal Government Affairs program (SLGA) within the American Chemical Society's Department of Gavemment Relations and Science Policy will aid ACS members in pmduetively interacting with their state and local deeisianmakers. The initial focus of the Proeram will be science education a t the elementaw and secondary level. Wide acceptance of the need to reform education in the United States exists. Efforts by the Nation's governors and recent congressional passage of legislation supporting the development of national standards testify to this fact. While the American Chemical Saiety and many other groups contribute to Congress's development of federal education policy, much of the reform activity is centered a t the state and local levels. The SLGA program will help fill this niche and build on the work underway in many ACS Local Sections across the country. Through distribution of information on related bills pending in state legislatures and on local reform measures, the Pmgram will enable ACS members to become a force in shaping education reform to the benefit of the sciences. A Public Affairs Kit, newsletter, and other materials will allow even those previously unversed in dealing with public officials to get involved. State legislatures offer a unique opportunity to affect public policy on a wide range of issues affecting chemistryfrom edueation to environmental protection. Legislators a t the state level are much more accessible than their Washington counterparts. Many also hold other full-time jobs, making the availability of reliable and informed advice fmm constituents vital. With approximately 150,000 members i n 186 Local Sections across the country, the American Chemical Society is well situated to provide such information. The mix of its members'industrial, government, and academic backgrounds affords the Society credibility lacked by groups representing narmwer interests. In the education area, the Society Committee on Education (SOCED) is providing policy direction to SLGA. SOCED bas selected several areas for emphasis: (1) measures dealing with teacher training and qualifications, (2) accountability for federal funds, and (3) programs to attract and retain populations underrepresented in the sciences. Afivemember Advisory Board provides strategic direction. The Board includes chemical professionals from industry, academe (precollege, two-year, and four-year institutions), and government (a state legislator). To maximize its impact, SLGA has selected 15 target states in which ACS member networks will be established: California, Colorado, Delaware, Florida, Illinois, Massachusetts, Michigan, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Texas,Washington, and Wisconsin. Members may request further assistance for other states or an additional issues. While intended far American Chemical Society members, the SLGAnewsletter also will be useful to others following science education reform developments. Ta receive the free newsletter and other information about the SLGApragram, contact Bill Gray of the SLGAstaff. He i s a t the American Chemical Society, 1155 Sixteenth Street, NW, Washingtan, D.C. 20036,202/872-4391 (phone), 2021872-6206 (fax), or wtg93Bacs.org (Internet). ACS members requesting information are asked to identify their Lacal Section affiliation.
David R. Schleicher Depattment of Government Relations and Science Policy American Chemical Society Washington, DC
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