Literature Cited 1. Bald%", W;Burchill, C. J Chom. Edue 1987,M. 1067. 2. Starkey, R.; Norman, J.; Hktze, M. J Chorn. Edue. 1386.63.473474
Ralph J. Thompson Eastern Kentucky University Richmond. KY 40475
and by using the value of the "buffer" for [H30+1. As a conclusion I would like to quote the good old maxim I learnt when I was a student: "It is unfair to ill-treat weak acids for the sole reason that they are weak and cannot react" (5). Literature Cited
To the Editor:
Andrea Tappam Universita di Padova Dipartimento di Chimica lnorganica Metallorganica ed Analitica via Marzolo 1, 1-35131 Padova, itaiy
In their microscale synthesis of cis- and tmns-diamminedichloroplatinum(II)Singh, Szafran, and Pike (1)masterly illustrate a number of important principles, including Chernvaev's trans effect (2). However.. thev" fail to cite an ear1ie;macroscale synthesis of these isomers (3)that does not reouire the ~reliminarvoreoaration of the corresoond. ing cis-diiodo compound. Because of the widespread use of ~ i s - [ P t C l ~ ( N H(cisplatin) ~)~l as an antitumor agent, this synthesis became one of the most frequently consulted papers in the scientific literature and in 1987 was recognized by the Institute of Scientific Information (IS11 as a "Citation Classic" (4).
..
To the Editor:
It should be emphasized that there are two distinct approaches to equilibrium calculations. The approach used by Baldwin and Burchill (1)employs the thermodynamic formulation using actvities. This approach leads to the result that K, for hydronium ion is unity and K, of water is 1.0 10-l4(= K, 1. The second approach, which I used in my article, employs the use of K, values based on the law of mass action in which molar concentrations are used instead of activities. This latter approach is nearly always the one by which students are introduced to the concept of weak acid and weak base ionization constants. The thermodynamic approach does make special cases of water and hydronium ion K. values. However, it seems prudent from a pedagogical standpoint to treat water and hydronium ion in accordance with the conventions of the law of mass action, since this is used in formulatingK, values of other acids. Tapparo's comment t h a t I borrowed this idea from Starkey, et al. (2) is about half true. But his assertion that K.= 55.4 for hydronium ion was refuted by Baldwin and Burchill is simply not correct (disputed, yes; refuted, no). One useful aspect of K, values is that they permit us to compare relative strengths of weak acids. If we take K, of water = 1.0 x 10-l4(as based on activities), then we might incorrectly judge ethylene glycol (K. = 6 x 10-15) to he a weaker acid than water. Actually, the reverse is true. The K, of water based on the law of mass action is
George B. Kauffman California State University, Fresno Fresno, CA93740 Literature Cited 1. Singh, M. M.: Szafran, Z.;Pike,R,M. J. Chorn. Educ 1990.67, A261. 2. Golovnya, V A,: Leonovs, T. N.: Craig, W; ffiuffman, G. B. Arnbir 1376, 23, 181; Kauffman, G.B. J Chem. Edur 1377.64,86:ffiufhan, G.B. Claspics in Coarhnation Chemietly, Port 3: %entroth-Century Pmmm 119WI9351: Dover: New York, 1978: pp 142195. 3. Kauffman, G.B.; Cowsn. D . O.7nog Syn. 1863.7.239. 4. K a u h , G.B. Current Conants: Phys., Cham., 8: Earth Sci. 19W28(61,20.
To the Editor:
Our paper "Microscale Synthesis of cis-Diamminedihaloplatinum(I1) and a Corresponding trans Isomer: A Rapid and Convenient Method of Preparing Cisplatin-An Anticancer Drug" (Singh, M. M.; Szafran, Z.; Pike, R. M. J. Chem. Educ. 1990,67, A2611 deals with a microscale laboratory practice for chemistry students. This laboratory cxpcrlment involving the synthesis of a crs-diiodo intermediate was develooedon the basis of the literature ouoted in it is up to the readers to take note of the paper. Professor Kauffman's paper, which describes macroscale syntheses of a series of Pt(I1) compounds including cisplatin.
ow ever,
Mono M. Singh Merrimack College North Andover, MA 01845
Accidental Degeneracies of the Particle in a Box
which does indeed correctly show water to be a weaker acid than ethylene glycol. My article was-directedmainly a t lower level undergraduate instruction. The thermodvnamic treatment of eauilibrium can wait until physical chemistry I must admit that I chose a Door examole for calculatine the extent of reaction between hydroniuA ion and aniline. My equation for calculating a does not work because the equilibrium concentrations of products are not equal. There is a concentration dependence. However, the equilibrum constant that I calculated, K = 2.39 x lo6, is still correct, showing that the reaction goes very far to the right. 516
Journal of Chemical Education
To the Editor:
In reference to mv note IJ. Chem. Educ. 1990.67.9991 R. M. Mazo ( ~ n i v e r s iof0Eegon) i~ has called my attention to the work of G. B. Shaw [J. Phys. 1974, A7, 1537-15461. Shaw showed that the accidental degeneracies of the states of a article in two-dimensional sauare. or trianrmlar, boxes are related to rings of operatok rather thanto the symmetry groups. C. A. Hollingsworth University of Pittsburgh Pittsburgh, PA 15260
