Comment on “Oscillations in the Bromomalonic Acid/Bromate System Catalyzed by [Ru(bipy)₃]²⁺”

Influence of Visible Light and Malonic Acid Derivatives on the Autocatalytic Oxidation of Ru(II) by Bromate Ions

“…First we reproduced and confirmed the results by Pereira and Faria, who showed that the inflection times of the Ru(II)-bromate autocatalytic system (no organic substrate or chloride ions present) is significantly dependent even on small initial variations in HBrO 2 (data not shown). To use a consistent set of initial concentrations in our calculations (which also reflects the mixing order in our experiments), we determined the steady-state concentrations of the inorganic bromo-species for a 0.05 M BrO 3 - solution (in the absence of the catalyst) and used these values together with the initial concentrations of Ru(II) and organic substrate as the initial start concentrations for the calculations (Table ).…”

Simulations of the Iodine Interphase Transport Effect on the Oscillating Bray−Liebhafsky Reaction

“…Other important information that is usually omitted when reporting kinetics simulations is the initial concentration values for species not present at the reaction beginning as was recently pointed out by Pereira and Faria. 16 To avoid a divide-by-zero condition when exact zero starting values are attributed to some concentrations, for many numerical integrators it is necessary to set an arbitrary concentration "background" of level, say 1 × 10 -10 M, for all the species not initially present. This is not the case when integrators with both absolute and relative error tolerance control, such as the ODEPACK package routines, are used.…”

Comment on “New Experimental Data and Mechanistic Studies on the Bromate−Dual Substrate−Dual Catalyst Batch Oscillator”

“…2 Initial concentrations formally considered as zero were indeed 1 × 10 -10 mol dm -3 background concentrations. 3 However, calculating Figure 9 for the bromate-acetone-Ru(II) subsystem, we have found that [Mn(III)] oscillates in a concentration range, approximately 100 times higher than [Ru(III)], even when [Mn(II)] 0 is equal to zero, as can be seen in Figure 1. The reason for this is that (R3) is a kind of global reaction that produces Mn(III) even when no Mn(II) is present.…”

“…All numerical integration has been done using a program written by Dr. István Lengyel in Turbo Pascal 6.0 and adapted to Free Pascal 2.0.4 to solve autonomous ordinary differential equation systems by a semi-implicit Runge−Kutta method . Initial concentrations formally considered as zero were indeed 1 × 10 −10 mol dm −3 background concentrations …”