The effect of various electrodes on the character of the course of chemical oscillating reactions Briggs-Rauscher

D. A. Usanov ; A. P. Rytik ; O. Yu. Kutikova

Izvestiya VUZ. Applied Nonlinear Dynamics, Tome 27 (2019) no. 5, pp. 87-94.

Résumé

Purpose of the present study is to determine the sensitivity of chemical self-oscillating reactions to various types of electrodes: silver chloride electrode, carbon electrode, platinum electrode. Methods. The objectives of the study were to identify the degree of influence of the measurement system on the parameters of the Briggs-Rausher self-oscillating reaction process, to determine the sensitivity of the self-oscillating regime of BR to micro-impurities of the salt of KSL, since it is part of the electrolyte of the silver chloride electrode, as well as to determine the optimal system for measuring the self-oscillating process of BR. Results. Parameters of the Briggs-Rausher self-oscillating reaction using different electrodes: ion-selective electrode (iodide) and reference electrode (silver chloride electrode, carbon electrode, platinum electrode) were investigated. It is shown that the use of a silver chloride electrode can make changes in the parameters of the self-oscillating process of the Briggs-Rausher reaction, due to the high sensitivity of the reaction to the impurity associated with the diffusion of the electrolyte from the silver chloride electrode. Electrolyte overflow occurs in sufficient quantities, in which there are changes in the nature of oscillations, namely, this affects the number of oscillations, reaction life time, amplitude. The reaction period when using a pair of silver chloride electrode and ion-selective electrode (iodide) is longer than when using other electrodes. The largest number of oscillations corresponds to the results using a carbon electrode and a platinum electrode, and the smallest using silver chloride electrode. Carbon and platinum electrodes due to their chemical inertness do not make any changes in the chemical composition of the test solution. Conclusion. Based on the results obtained, it can be concluded that the carbon and platinum electrodes, due to their chemical inertness, do not make any changes in the chemical composition of the studied solution, while the silver chloride electrode introduces changes in the medium of the reaction used by adding micro-quantities of KCl impurities. Presumably, the electrolyte solution, which is present in the electrode, gradually flows into the reaction medium through the asbestos fiber and the salt bridge. Electrolyte overflow occurs in sufficient quantities, in which there are changes in the nature of oscillations, namely, this affects the number of oscillations, reaction life time, amplitude. Thus, it can be concluded that the silver chloride electrode is not suitable for use as a reference electrode for measuring the parameters of the self-oscillating mode.

Détail

Keywords: self-oscillating reactions, microconcentration, electrode, electrochemical potential.