Procedure for Processing Experimental Kinetic Curves to Determine the Rate Constants of Gas-Phase Chemical Reactions

Topical questions of constructing a model for measuring the rate constants of gas-phase chemical reactions are considered. These questions include aligning the experimental conditions and the initial data for a system of kinetic equations, constructing analytical models of kinetic curves, and estimating the rate constants for the reaction considered and the secondary processes. Using the example of one of the important chemical reactions, OH + O → O2 + H, which is a part of the mechanism of combustion of a hydrogen-oxygen mixture, the problem of selecting the optimum method for processing the experimental kinetic curves is solved. The optimization criterion is obtaining a more complete volume of information on the rate constants of both primary and secondary processes, as well as the fulfillment of requirements for the convergence of the results of the iterative process for determining the rate constants for different experimental conditions for obtaining the kinetic curves and identical conditions that determine the measured quantity. The principle of “invariance of the measured quantity” is used to estimate the rate constants of secondary processes. This principle states that, under the experiment conditions that the measured quantity is constant, the method for determining the quantity should ensure a minimum range of variation in its values. In constructing the model and its optimization, for four processes in the base set (58 reactions), the changes in the rate constants were recorded at the temperature T = 298 K under the experimental conditions in which molecular hydrogen serves as the source of hydroxyl OH.