Temperature Dependence of the Exothermic Gas-Phase Reaction Rate Constants at Temperatures up to 500 K

The aim of the study is to increase the accuracy of determining the gas-phase chemical reaction rate constants by means of numerical methods. The problems of justifying the choice of regression functions and refining their parameters in determination of the temperature dependence of the exothermic reaction rate constants are solved. The methods of solving are aimed at detecting the uncertainty components of the regression parameters associated with systematic effects, followed by their elimination or compensation. The specific features of using the Arrhenius law to approximate the temperature dependences of exothermic reactions are found from the results of numerical investigations. Despite the universal form of the law in the chemical reaction kinetics field, the utility of using the Arrhenius law as a universal model can be called into question in the regression analysis of experimental data. It is found that the unjustified choice of the regression model serves as a source of an additional uncertainty of the regression parameters, the revealed correlation dependence of the parameters results from the excessive complexity of the model. It is demonstrated that a simpler model based on a power-law function describes the temperature dependence of the exothermic reaction rate constants fairly well. Particular calculations and estimations are carried out with reference to the OH + O → O2 + H and O3 + H → OH + O2 reactions over the temperature range from 150 to 500 K.