Chemical Education Today
Letters Ethics for Scientists I applaud the recent article by Jeffrey Kovac (J. Chem. Educ. 1996, 73, 926) in which our attention is directed towards the need for ethics in science and his efforts to develop texts and materials for classroom use. It is encouraging that articles discussing the inclusion of ethics in the chemistry curriculum are appearing more frequently in this Journal (e.g., J. Chem. Educ. 1996, 73, 33). I do however, take issue with Kovac’s use of “Scientific Ethics” in both the title and the body of the article, which implies that environmental, biomedical, and religious ethics are nonscientific. Colleagues active in these areas publish scholarly work that is genuinely “scientific”. I would suggest using “Science Ethics” or “Ethics for Scientists”, since that is really what the paper is about and is more inclusive language. My concern is one of nomenclature which for chemists is of great importance and does not lessen in any way the solid foundations of Kovac’s contribution.
Beer–Lambert Law On page 100 of the article “The Spectrophotometric Analysis and Modeling of Sunscreens” of the January 1997 issue of the Journal of Chemical Education is one of the common errors of today’s indifference to sloppiness: Beer’s law provides a relationship among absorbance, molar absorptivity (ε), path length (b) and molar concentration (c): A = εbc
This equation is not Beer’s law; it is the Beer–Lambert law. Beer’s law is A = kc; b is constant; k is a × b, or in the form for molar absorptivity, k is ε × b; a is absorptivity. Lambert’s law is A = k′b; c is constant; k′ is a × c, or ε × c. Please, as Editor, stop the lazy sloppiness of misnaming the Beer–Lambert law. There is a Beer’s law, and it is not the Beer–Lambert law. Dean Calloway 27 Ridgewood Drive Columbus, MS 39701
Shaun O. Sommerer Department of Physical Sciences Barry University 11300 Northeast Second Avenue Miami Shores, FL 33161-6695
Double Redox Reactions Kovac replies: The term “scientific ethics” is commonly used to refer to the ethics of the practice of science, just as medical ethics refers to ethics of the practice of medicine and legal ethics refers to the ethics of the practice of law. Neither in common usage nor in my article is there any implication that scholarly work in the ethics of other professions is any less “scientific”, whatever is meant by that term. My own thinking has been strongly influenced by the excellent scholarship of colleagues writing on the ethics of fields outside of science, as I have acknowledged in my article. I agree that there might be confusion because the adjective “scientific” is sometimes used to suggest that the scholarship is somehow more rigorous. John Dewey, for example, favored science education for children in hopes that they would develop “scientific habits of the mind”, which he viewed as desirable thinking habits. Perhaps a new term is needed to avoid the confusion, though I hope that our colleagues outside of science do not assume that the adjective scientific is being used to subtly denigrate their work. “Science ethics” is nicely parallel to business ethics and engineering ethics, so it would serve. The more cumbersome “ethics for scientists” or “ethics of scientific practice” are alternate possibilities, but none of the alternatives comes off the tongue as nicely as scientific ethics. Names are powerful. If the term scientific ethics is troubling to ethicists outside of science, it should be replaced. If not, I prefer to retain the more felicitous phrase. Jeffrey Kovac Department of Chemistry University of Tennessee Knoxville, TN 37996-1600
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Cardinali et al. proposed an interesting procedure to balance double disproportionations (J. Chem. Educ. 1995, 72, 716). The combination of two reactions containing suitable “extraneous” species as co-reactant and co-product can be used to balance not only “pure” double disproportionations, but double redox reactions, too. For example, we can balance the equation KI + H2O + C 2H5OH → K2CO3 + H2 + CHI3 by introducing KOH as “extraneous” species into the two redox reactions between C2 H5OH and H2O: C2H5OH + H2O + 4KOH = 2K2CO 3 + 6H 2 C2H5OH + 6KI + 5H2O = 2CHI3 + 4H2 + 6KOH After eliminating the “extraneous” species KOH, we obtain the balanced redox equation: 5C2H5OH + 12KI + 13H2O = 6K2CO3 + 26H2 + 4CHI3 Zoltán Tóth Lajos Kossuth University H-4010 Debrecen, P.O. Box 66, Hungary The authors reply: The chemical equation proposed and brilliantly discussed by Z. Tóth, referring to the electrolytic production of iodoform (a quotation would have been helpful), exhibits quite interesting stoichiometric features.
Journal of Chemical Education • Vol. 74 No. 7 July 1997
continued on page 760
Chemical Education Today
Letters continued from page 744
Strong Acid with Strong Base
Clearly, it is not a multiple-stoichiometry equation, since five nonequivalent atomic conservation relations are available to assign the six stoichiometric coefficients, so that it can be readily balanced by the algebraic method (1). The same is no more true when employing the (traditional) oxidation-number method, because ethanol gives origin to two different oxidation products (each containing carbon with a different oxidation number) such that the ratio of their amounts (numbers of moles) cannot be established a priori. Minor difficulties arise from the facts that the (only) reduction product (formally) takes origin from two different species, one of which is also the source of the oxidation products; furthermore, in this equation, hydrogen plays a dual function (2), partly behaving as a redox, and partly as a nonredox, element. Therefore, Tóth’s equation represents a third case where, while the traditional oxidation-number method fails, our approach, which splits the equation into two simpler ones, each involving the participation of the same “extraneous” species as co-reactant and co-product, succeeds; the other two cases are the double disproportionations (3) and the rather uncommon equations of the kind elsewhere (4) discussed by us, for which we would propose the name of dis-co-proportionations. Finally, we would observe that Tóth’s equation could have been balanced also by employing the recently published (5) more general version of the oxidation-number method which makes use of oxidation-number concepts in an algebraic-method framework.
For the addition of a volume Vb of a strong monoprotic base MOH of concentration C b to a volume Va of a strong monoprotic acid HA of concentration Ca, de Levie states that the general form of the titration curve in this case gives a quadratic equation for [H+]. Specifically this is + 2
H
–
C aV a – C bV b + H – Kw = 0 Va + Vb
(1)
where Kw = [H+][OH{]
