Figure 5. Simulated conductivity data for titration ol strong acid with strong base.
Figure 0. Simulated conductivity data for weak acid with stmng base.
choose and key in concentrations and volumes of hydrochloric and ethanoic acids in the flask as well as the concentration of sodium hvdroxide in the buret. The total conductivity, as observed in a laboratory experiment, is displayed on the screen and shows two breaks in the curve. indicatine the tu'o equivnlence positions (Fig. 6). The \wlumes 01' sodium hsdroxide reauired to titrate the strong and weak acids ar; numericall; indicated on the screen to enable the student to analyze rapidly . . the contents of the acid mixture. Program listings suitable for the Sinclair Spectrum 48K instrument are available. In order to cover airmail postage, handling, and printing costs please send a money order to the author for N.G. Kina 3 or $5 (Australian) or $4 (US.).
and programmed i t for a Commodore 64 microcomputer. Once students have mastered fundamental principles for transformine" a matrix most can balance even the most difficult equations in less than a minute. No knowledge of oxidation numbers is reauired. The matrix is easilv constructed nnd consists of numbers that indicate the toial number of atoms ot'enrh elrmcnt in each compound. The tmnsformations involve only simple addition,suhtraction, multiplication, and division of numbers in the matrix. The computer program uses the same method to balance equations in less than 10 seconds. A detailed description of the method, several examples of its use, and a copy of the computer program for a Commodore 64 are available from Project SERAPHIM.
titration of e mixture of strong and
Literature Cited
Balancing Chemical Equations with a Commodore 64 Wllllarn Loercher Donegal High School Mount Joy, PA 17552
Pmc. Combridge Phil. Sa'. 191O.15.423. Herrben, G. "Molecular Swetra and Molecular Structure. 1. Smtra of Diatomic MOI~&I..-. 2nd ed.; ~ ~ ~ ~ o s New t mYork. ~ d 1950. : (3) Sfsfford, F.E.;Holt, C. W.: Paulson, G.L. J . Chrm. Edue. 1963,40,245. 14) . . Bork.. A. Amer J.Phvs. 1980.4&421. (5) ~ m w nH. , A. ~ m e i r ~hys. is&,5a.905. (6) Shuk1a.S. S.: Rusling, J. F.And. Chem. 1984.56,1347A. (1) Bstemsn, H.
(2)
(7) Hamming, R. W. '"Numerical Methods for Scientists and Engineers". 2nd ed.: McGraw-Hill: New York. ,973: p 4. 181 inn41. , ~ ~~t , . (91 Ret (71.~43. (10) Huff.R.B.:Csrter.K. N. J. Chem Edue. 1981.58,49. (111 Solberg, H. E.Anoi. Chem. 1983,55,1611. (121 Sane. K. V. Inf. Neudrttor Chem. Educ. IUPAC 1982.17,9. (13) UNESCOIIUPAC "Locally Produced and Low Cost Equipment for Chemistry Tea~
The enigma of balancing equations has both intrigued and ~ernlexedchemistrv students for eenerations. Traditionallv students have relied on the triacand-error method. s o m i become quite proficient, hut many more seem never to understand fully or develop the skill. I have developed an array transformation method similar to hut simpler than matrix methods reported previously (16)
74
Journal of Chemical Education
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114) Holdsworlh. D. K. Comm. 7th Int. Conf Chem. Educ (Montpellier. France) 1981.2.
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