A Program for Numerical Integration of Reaction Rate Laws on the Basis of the Runge-Kutta Method.

Yuji SHINOHARA*,Tsuyoshi NAKAJIMA,Shozi MISHIMA

(Recieved : September 24, 1996 ; Accepted for publication : October 21, 1996)

A computer program was prepared to calculate time-courses of concentrations of chemical species involved in a chemical reaction. On the basis of Runge-Kutta iteration method, the program integrates numerically simultaneous differential equations which express relations between the concentrations and the rates of these changes.The program was designed to monitor the rates for all species from moment to moment, to select the best-suited iteration interval for the integration and then to carry out the integration with the interval. The program was applied to the following reaction systems: 1) oscillatory reaction in an aqueous solution of IO₃^-, H⁺, I₂, I^- and H₂O₂; 2) saponification of ethyl acetate; and 3) gas phase chain reaction of bromine with hydrogen. The results showed that the program gave accurate time-courses of the concentrations of reactants and products in relatively short processing time.

Key Words: Runge-Kutta method, Numerical integration, Rate law, Computer program, Simulation

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