Reversible Oregonator model revisited: Thermodynamic validity

We have investigated the features of thermodynamic equilibrium state of the reversible Oregonator (RO) model with close system approximation for a plausible stoichiometry, in which there is no overall change in the concentrations of the intermediates. For Field-Försterling (ff) parameters, this model with close system approximation attains the state of thermodynamic equilibrium at equilibrium concentration of its final product in the order of 104 mol l-1, which is obviously unrealistic in a laboratory experiment. From numerical experiment, we report that if the equilibrium constant of the fifth step (K5) is assigned a value less than 1.0 (which is opposite to that proposed by Field), the RO model under open system approximation could execute oscillations, as well as under close system approximation could evolve to a thermodynamic equilibrium state with reasonably low and realistic equilibrium concentration of its final product for the overall reaction considered here. To accommodate the findings of this numerical work for the RO kinetic steps with K5 <1, we have found it necessary to revise the 2-variable diffusion-reaction model of Tyson.