W. D. Moebs and E. A. Haglund Ft
Purdue Un~versliy Wayne, lndlana 46805
A Simple Monte Carlo Method for Teaching Chemical Kinetics
Chemical curricula have gone through extensive changes in the last decade or two. The areas of atomic and rnolecul&r structure and quantum chemistry have been greatly developed over this period. Much of this material has been added to various courses in chemistry a t practically all levels. T o make room for this newer material, some other chemical topics have been either eliminated or treated superficially. Consequently, certain basic areas such as chemical kinetics have been neglected-particularly on the undergraduate level. The junior or senior physical chemistry course usually spends one to three weeks on the entire subject. The simple differential and integrated rate laws and related experimental techniques are usually covered first, and any remaining time is spent on rate theories and analytical relationships between proposed mechanisms and observed rate laws. These topics are considered basic to the general subject of chemical kinetics. However, they give little insight into what is actually happening to the various chemical species involved, even in fairly simple reacting systems. This paper deals with a relatively simple computer program which can be easily used to generate and "follow" reactions that can he simple or complex. The concentrations of all involved species (reactants, products, and intermediates) are given as functions of time. The available rate data and proposed mechanisms serve as input, while output involves the concentrations as functions of time. Results which are usually approximated and expressed as ahstract mathematical functions are expressed directly as superimposed plots. The examples illustrate how the technique can be used withminimum effort as an aid in teaching chemical kinetics a t the introductory and intermediate levels. The computational method is based on a Monte Carlo generation of a large number of chemical reactions. The relative probabilities of all possible reactions are compared, and the reactions are then allowed to take place on the basis of these relative prohabilities.
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Figure 1. The time developmeot of &mica1 meentratians in readion (I). The sold lines rewesent the R u n g e X W ihtegration and the designated points Monte Carlo calculations. (a) 0.0 < 1 10.0(b) 0.0 t 1000.0. represent
