An Introductory Level Kinetics Investigation
J. E. 0. McGarvey and A. C. Knipe The New University of Ulster N. Ireland
A feature of modern introductory courses in chemistry is the importance given to the study of reaction rates and mechanisms. This is a recognition of the central role that kinetics and mechanisms play in the understanding of chemistrv. Most of the reactions which are commonlv used (Table ljto give students an experimental introductiodto the subject of kinetics are of an illustrative nature and are used to introduce the concepts of rate law, rate constant, and reaction order. These reactions are selected because of their suitability for the experimental determination of the reaction rates, hut in only a few cases is the mechanism sufficiently straightforward for the introductory level student to appreciate the link hetween the kinetics. the nature of the rate determining. step, . and the likely renclim mecl~anism.F~~rthermt,re, the reartions for vxtmded in\,estirntUm 10 highly nrewnt 111111,u~portunitv .. motivated students, or fbr incorporation in gr&p projects. As a result of such experiments students may understand the mathematical principles of chemical kinetics and yet fail to appreciate the importance of kinetics in elucidation of reaction mechanisms or fail to recognize the type of chemical problems to which the experimental kinetics approach may be applicnhle. -~ Ashmore 1 I I h.15 argued that students sh~luldmeet experimental insr:st~eationsin whirh t hr study of ratesand mwhanisms go handin hand so that the kinetic results can he interoreted meaninafullv. - - Campbell(2) points to the dearth of susahle rate experiments which meet these criteria and suggests that there is a need to develop a larger number of suitable investigations a t the introductory level. With this in mind, we describe a kinetic study of the hydrolysis of 3hromo-3-phenylpropanoic acid which offers the following experimental advantages. ~
1) The apparatus is very simple, and so inexpensive class sets may he omvided. 21 'I'hestarring material is readily prepared i n high sield hy a m e step synthr..ii, w h ~ t his approprtnre fur studenlaar thiq level and x h i n cr
