provocotive opinion A Question of Basic Chemical Literacy? Ronald W. Missen Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto. ON, Canada M5S 1A4 Wllllam R. Smith Department of Mathematics and Statistics, University of Guelph, Guelph, ON, Canada N1G 327 Over the years the pages of this Journal have devoted much space to the problem of "chemical equation halancing". This is almost always done in the context of a chemical system that requires only one chemical equation for its stoichiometric description. Important as this situation is, particularly in analytical chemistry and electrochemistry, emphasis on i t can have unfortunate concomitants and consequences. This is a result of the following: (1)the description may involve imprecise language, and the emphasis (2) may detract from the larger aspects of the stoichiometric description and (3) may leave false impressions in the mind of a student. The result may be that basic chemicalliteracy isnot as well developed as i t should be; by "chemical literacy" we mean the ability to read and write clearly in chemical-equation terms in a general sense. The purpose of this "Provocative Opinion" is to draw attention to a perceived problem, not by any means for the first time by interested parties, and to suggest specific remedies for its solution.
represent the stoichiometry, a consequence is that any interchangeability of the words "equation" and "reaction" is lost. The chemical equations simply represent conservation statements and have no necessary significance as reaction statements (2). Emphasis on one-equation systems in teaching "halancing" without paying attention to the questions of the appropriate number of equations to use can result in misleading and lasting impressions in a student's mind. Thus, a student may feel that areactingsystemranalwoys herepresented by an equation and the "trick" is to be able to find it and write it properly. The idea that species react in fixed proportions (true only for a one-question system) becomes firmly embedded in the student's mind as though it were a universal law of chemistry. An example cited by Jensen (5) seems to illustrate the situation.
The Problem
With regard t o precision of language, we first note, as has undoubtedly been observed before (cf., e.g., ref I), that an expression like "balancing a chemical equation" is a contradiction of terms. Furthermore, a chemical equation, in the stoichiometric sense, is fundamentally a conservation statement about atomic species. When only one such statement is required, we tend to slip into the conceptual framework of identifying the equation with the (overall) reaction, in the sense of reactants forming products, and use i t as a reaction statement. The words equation and reaction then tend to be used interchangeably. This can have unfortunate consequences, as we explore below, but a t this point we note this practice as another example of the use of imprecise language. (We exclude a t this point consideration of a reaction mechanism, for which more than one reaction statement is usually required even for a one-equation system.) The larger aspects of the stoichiometric description of a chemical system relate to the number of chemical equations required and the means of writing a permissible set. I t is implicit in most treatments of "halancing" that only one equation is required and yet this is rarely justified a priori. Methods of addressing these larger aspects have been known for some time (see bibliography up to 1976 in ref 2), hut do not appear to have entered the realm of everyday working tools, particularly in terms of introductory teaching and learning. Some of the recent contributions in this Journal (3-5) haue dealt with these larger aspects, but the emphasis has been on "equation balancing", as indicated by the titles used. When two or more chemical equations are required to
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