Chemical Education Today
Letters Let’s Dot Our I’s and Cross Our T’s I read with great interest the letters “Redox Challenges” by David M. Hart and by Noel S. Zaugg (J. Chem. Educ. 1996, 73, A226), the article by R. Stout that they both had cited, and the author’s reply to the polemics. I was intrigued also because I knew very well that I had read about this “Chemical Monster” many years ago in this Journal ! Unfortunately I didn’t remember even the year of publication; Chem. Abstr. also didn’t mention that particular article. Nevertheless after two days of searching I found what I was looking for in the November issue, 1943, on page 570. Here is this very short unsigned article: “Try This One! L. S. Foster, until recently one of our associate editors, sent us the following equation to balance. The editor bears witness that it can be done—although it took $1.27 worth of his time (at current rates) to do it. We’d like to know who can do it in the shortest time. Ready—go!” And below was the famous equation [Cr(N2H4CO)6]4[Cr(CN)6]3 + MnO 4– + H+ → Cr2O7= + CO2+ NO 3– + Mn ++ + H2O
So we can see again that “There is no new thing under the sun” (Ecclesiastes, 1:9)! But I wonder whether anybody knows the salary of the editor in the midst of 1940s to estimate the time necessary to balance the equation in minutes instead of hard currency? Equally marvelous was the first reply to that challenge in the “Out of the Editor’s Basket” column. Norris Rakestraw wrote on page 30 in the January issue, 1944: “We received a number of solutions to the equation which appeared in the November issue (page 570). All three of the common methods were represented: the “valence change method,” the “ion-electron method,” and the “algebraic method.” The best time was reported by Miss Dorothy Elkind, of Villa Park, Illinois, who used the algebraic method and who says, “By the method outlined, it does not take more than 15 minutes to balance the equation.” We assume that this was her time, although she doesn’t actually say so. If not, the speed record goes to another contestant who reports “less than 16 minutes”—but whose solution didn’t balance!... Various interesting comments were offered, including the suggestion of assigning arbitrary zero valence numbers to all the elements in the complex, which of course leads to a correct solution if consistently followed...” But my own opinion is that all these puzzles are nothing more than mathematical and, partly, chemical “games” because it is highly improbable that such “monsters” are stoichiometric equations! Directly connected with this question is the article by William C. McGavock “Nonstoichiometric Equations” (J. Chem. Educ. 1945, 22, 269) and many others published in J. Chem. Educ. from the first issues (see, for example, 1926, 3, 425–431, 1430–1431; 1927, 4, 1021–1030, 1158–1167; 1929, 6, 479–485, 527–535, 1136–1138; 1930, 7, 1180, 1688–1693). In the end I would like to quote Leo Lehrman from The College of the City of New York. He
wrote 66 years ago: “To make such practice a mere mathematical exercise…is to put us back many years” (J. Chem. Educ. 1932, 9, 944–945). Ilya A. Leenson Department of Chemistry Moscow State University 119899 Russia
Formation and Dimerization of NO2 I have strong misgivings about the article, “Formation and Dimerization of NO2” (J. Chem. Educ. 1997, 74, 1340– 1342). Aside from the unfortunate implication in the calculations that individual gases in a mixture occupy separate volumes, there is an overriding disadvantage to the experiment described: The results are terrible! A student who has any intuitive feel for quantitative relationships will be appalled by the scatter in the values obtained for the equilibrium “constant” and its distance from the accepted value. What appalls me, as one who spent 30 years trying to impart to students the faintest glimmer of the notion of “significant figures”, is the statement by the authors that 2.7±1.0 “compares reasonably well” with 8.6! More important, the beginning scientist may not know whether this is the result of poor data, or an innate characteristic of the scientific method. The implication that these are the kinds of data upon which the law of combining volumes is based will mislead the typical student, and confuse the circumspect one. The authors begin by observing that “experiments demonstrating…law of combining volumes are virtually absent” from general chemistry lab manuals. What their article illustrates most clearly is the reason for this observation: Successful performance of such an experiment is technically very demanding, and beyond the abilities of the typical general chemistry class. What would be the effect on a neophyte piano student of expecting him or her to play “The Minute Waltz” before ever having practiced scales? Discouragement and disillusion, surely, and perhaps the urge to try a different instrument! Edwin F. Meyer Emeritus Professor of Chemistry, DePaul University 1022 Dobson St. Evanston, IL 60202
Presidential Education Policy Aside from the fact that the editor of the Association Reports: 2YC3 is a member of the faculty of San Jacinto Community College, I cannot find a single additional reason for publishing President Clinton’s educational/political remarks which he presented at San Jacinto Community College (J. Chem. Educ. 1997, 74, 1392–1393). What’s next, a similarly vapid political reply from Gingrich outlining his contributions to balancing the budget and his desire to have “an educational system that works for all”? Harold T. McKone Department of Chemistry Saint Joseph College West Hartford, CT 06117
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Journal of Chemical Education • Vol. 75 No. 9 September 1998 • JChemEd.chem.wisc.edu
