Functlon Keys and Parameters

Description of the Function Keys

F1: inverts potential sweep direction. F2: stops potential sweep. A constant potential is maintained F3: shows species concentration profiles. F4: program pause. F5: gets a screen printing. F6: program initialization. F7: exit to DOS.

Input Parameters Range

Concentration (0 1 0 P < C < 5 ( M ) Electrochemical standard

rate constant (@) 0 < k0 < 10 (cm.scl) Chemical rate constant (k ) 0 < k < 50 ( 5 0 )

Diffusion coefficient (o) lo-' < D < lOW (~rn-~.s-') Transfer coefficient (8) 0 < 8 < 1 Standard potential ( P ) - 3 < P < 3 ( V ) Scan rate (v) -500 < v < 500 ( rnVC' )

The program developed can be used to simulate five of the most usual electrochemical mechanisms: simple electron transfer (Fig. 4), CE, EC, catalytic, and ECE (Fig. 5). Hard- ware required includes an IBM PC or compatible. If screen printings are wanted, an EPSON LX-800 or compatible dot matrix printer must he used. Program emulates a real vol- tammetric system in which i t is possible to stop or reverse the scan. Moreover, concentration profiles of all species can be displayed in each instant. Warning windows are opened when out of range values are input.

A complete description of the function keys and the input parameters range can be found in the table. A machine- readable copy of this program is available from Project SER- APHIM.

Glossary C w,r,: conrrntration <,isperies I nr diatanre x at timer. (' I1.r): conrmtmtrrm uf specie% I nr the electrode surface ar r i m t.

D : d:ii,mim ruefficiwt of species i . F: Faraday constant. f : FIRT

E: electrode potential. En: standard electrode potential 4: E - E". u;: stoichiometrie coefficient of species i (v, < 0 and uo < 0)

kO: electrochemical standard rate constant.

Interactive Computer-Video Programs Used in the Process of Chemistry Teaching

Hanna Gullnska, Ratal Lewlckl, and Andrzej Burewlcz A. Mickiewicz University

Grunwaldzka 6 60-780 Poznah. Poland

The main aim of methodological classes on chemistry teaching held in universities in Poland is to educate the future teachers of chemistry how to use modern and multi- media technioues in their future work (21). ~~ ~ . .

In our laboratory we have constructed a universal micro- nrocessor-based interface enahline interactive controllina of .~~~~~ video by a computer. This technological device creates a special experimental learning environment that allows the student, by operating the computer, to screen appropriate film pictures recorded in the video system (22).

The diagram showing the connection between the com-

Figure 6. Diagram of the connection of the interface with the video and computer. [I]-Interface. [2]-video. [3]-photoelectric module lor tracing the tape feed. 1414 set of miniature relays operating the video. [5]-a standard Centronics %rocamputer interface that controls the educational program.

nuter and a video is nresented in Fieure 6. Interface 111 is a " . . specialized computer programmed to operate the video 121. Since there are a ereat varietv of r,ideos. we derided that this interface would work as a tape counter enabling a search for the appropriate picture. To this effect, under one of the winding wheels we placed a circuit [3] to trace the tape. This circuit is made of two phototransistors, and it illuminates the rlectroluminescence diode. By miniature interface-ron- trolled relays 141, the push huttoni of video manipulatorsare

~ . . integrated with the close circuit. The tape-feed sensor along with the timers make the elements of the close circuit. Inter- face is a specialized computer, operating with its own lan- guage. Instructions in this language are transmitted to a comnuter hv a standard interface of the Centronics tvne 151.

u. . . ~he'instruckons and the values of the timers indicating the beeinnine and the end of the video Droeram are transmitted through ;his interface from the language in which the com- puter didactic program has been written. The interface is programmed in such a way that it will automatically perform the built-in functions, such as tape winding, stopping, and turning off the video. The interface also provides informa- tion about the actual position of the tape in the video.

The technical solution of the described interface is pro- tected by the right of patent application (23).

Thus, using the aforementioned integration between the computer and video, an educational program entitled "Steps in Chemistry Lesson Preparation" was developed. It is in- tended for the students and teachers of chemistry to use during seminars and classes on chemistry teaching as well as for individual work.

This program consists of three blocks (Fig. 7):

Block I-is s manual-driven control unit offering the user many problematic and testing tasks, questions, and hints.

490 Journal of Chemical Education

Block II: Informatton

Block I: User's Steps

Block III: Examples of Chemlslry Lessons: . A representative 01 aromatle hydroear.

bono-benzene. . PhysIcaI and chemlcal properties ol proteins. . Natural and modiiied polymers.

1. Structure of the teaching program. 1. Analysis of the tea 1. Examples of the analysis of the teaching program.

4 4 + + 2. Functions of me course book. 2. Analysis of the cont 2. Correspondence between the

teaching. course book and the program.

4 4 + 3. Examples of correlation.

maarematicsbiologiceI programs. subject correlation.

T

4. m e meory of selection of teaching 4. Examples of graphic-matrix analy- material. of the teaching content structure. sis of the lesson content.

4 + 5. Lesson goals taxonomy. 5. Determination of lesson aim.

4 + 6. Selection criteria of teaching 6. Examples of selection of methods.

methods.

t 7. Strategies of teaching. 7. Examples of different forms of

lesson organization.

4 + 8. Didactic devices in chemistry 8. Examplesof application of didactic

teaching. toods during lessons.

4 4

9. Safety In the chemistry laboratory. 9. Safety rules to be obeyed upon experimentatlon.

4 T

10. Homework--goals. types and 10. Exemplary homework. checking systems.

4 + 11. Recycling of knowledge. 11. Examples of revision exercises.

+ 13. Elements of syllabus. 13. Exemplary syllabuses of chemis-

try lesson.

Figure 7. Block scheme of the interactive cornpuier educational program: ''Steps in Chemistry Lesson Preparation".

Volume 68 Number 6 June 1991 49 1

Block II-contains a elossarv of didactic orohlems that can be used 2. Everdell, M. H, lntrudurlion to Chemical Thermodynamics: Norton: New York, 1965: ~~ ~ - ~ ~~ . 1,s t h e uwr in a n y stage of hlx work w i t h t h e provam.

B l o c k l l l - e x e m p l i f i r r t h e content of H l o r k a I and 11 and p r e s e n t s some exemplary chemistry lessons.

Blocks Il and 111 contain 3-7-min video seuuences. and Block I11 contains additionally several exemplary computer programs that show the possibility of using microcomputer in chemistry classes a t school. The blocks are interrelated, and the user may, as the need arises, use the program in a multifashion way. The presented program is also prepared in other languages, i.e., in English.

There is an open possibility that the program could be used by students of other departments, e.g., if the chemistry lesson in Block I11 were replaced by exemplary physics or biology lessons. At present we are working on an interactive videwomputer program that will deal with the problems of environmental chemistry.

Literature Clted 1. Denhigh. K. ThePrineiples o/ChemieolEquiiibrium:CamhridgeUniuersity:London,

1971.

Chapter 11. a. welrin. E. J, them ~ d u c 1990. in press. 4. Smith, W. R.; Miraen. R. W. J. Chpm Educ 1989,66.489. 5. Ailendnerfer. R. D. J . Chrm.Edur. 1990.67.37and referencescited therein: Douglaa,

J. E. J. Chem. Edue. 1990,67,42. 6. Slater, J. C. Phyr. Reu. 1930.36.57: Duncanem, W. E.: Coulaon, C. A. Ploc. Roy. Soc.

Edinburgh 1944, 62A. 37: Pauling. L.: Wilson. E. B. Infroduetian l o Quantum Mechanics; McCrsw-Hill: New Yark, 1835.

7. Lipkowitz. K. J. Chem.Educ. 1984,61.1051. 8. Lipkawitz, K. J. Chem. Educ. 1989,66,275. 9. Slmpaon, J. M. J. Chem.Educ. 1989.66.406,

10. Lil1ie.T S.:Yesger. K. J. Chom. Edur. 1989.65.675. 11. Bailey, R. A. J ChemEduc. 1989.66, 836. 12. Clark. T. A Handbook o/Com~ulolronol Chemistry: A Practical Guide Lo Sfrucfure

198J;Appendix. 15. Eng1er.E M.:Andose, J. 0.; Sehleyer,P.~.R.J, Am. Chem. Soe 1973.95, m05. 16. Rosenle1d.S.: William~,A.J. Chem.Educ.,inpresa. 17. Bard, A. J.: Fsulkner, R. In Eleclrochemicol Methods: Fundamentals and ~ p p l i ~ a -

wa-,. 70s" .. ...,, 18. Fe1dhere.S. W.Elecrroonal. Chem. (Ed. Bnrdl 1 1 6 4 . 1 199~ , 1% Blitz. Di&d Simulation in ~ ~ e c t r m h ~ m i e ~ ~ ; Spriner. 1981. 20. Kissinger. P.T.: Heineman. W. R. J . Chem. Edur. 1983.60.702. 21. Burewicz.A.:Gulifiska, H. J. ChemEdur.. 1990.67.56, 22. L. L. Jones. LOU1Inf. Conf. Chem Educ., Waterloo iOnt.Canada1, 1989 p RS01 23. Pal. Pat. P-286399 (1969).

492 Journal of Chemical Education