Simulation of the BrO3--Mn(III)/Mn(II)-H3PO2-H2SO4 Heterogenous Chemical Oscillator

Article abstract of DOI:10.1021/j100381a038

Experimental investigations and simulations have been carried out on the heterogeneous BrO3^--Mn(III)/Mn(II)-H3PO2-H2SO4 chemical oscillator as well as on component reactions expected to be important in it mechanism.Heterogeneous means that Br2 produced in the reaction is swept out by a stream of N2 gas.The core of the oscillatory mechanism is a Br2-hydrolysis-controlled version of the Field-Koeroes-Noyes mechanism.However, simulations base both on a radicla and on a simpler, molecular-ionic mechanism for the oxyphosphorus chemistry adequately reproduce the experimental behavior of the component reactions as well as that of the oscillatory system.Estimated values of ΔG_f⁰._(aq)>, ΔG_f⁰._(aq)>, ΔG_f⁰(aq)>, and ΔG_f⁰(aq)> do not exclude the radical mechanism but do indicate that the component reactions of the ionic mechanism are often much more highly favored thermodynamically than the component reactions of the radical mechanism.Furthermore, the ionic mechanism seems likely to be dominant on the basis of the simplicitly of the experimental kinetics of component reactions and the robustness of the behavior of the ionic mechanism to small changes in rate constant values.Some simulations of a system with Br2 removal by reaction with acetone rather than by gas bubbling were carried out but were not as successful as simulations of the heterogeneous system.