The oxidation of cerous ions by bromate ions comparison of experimental data with computer calculations

Abstract

The oxidation of cerous ions by bromate ions in sulfuric acid medium was followed spectrophotometrically under various experimental conditions. The results were compared to the calculated predictions on the basis of a mechanism suggested by R. M. Noyes and collaborators.The computations were done by solving the complete set of the kinetic differential equations. The results of the computations show that the proposed mechanism explains adequately most of our and previous experimental data. In particular, the mechanism predicts the main features of the reaction, namely, the induction and the fast and slow reaction periods which occur during the oxidation.

Chemistry of Inorganic Systems Exhibiting Nonmonotonic Behavior

“…However, in a strongly basic medium, Buxton and Dainton (1968) have directly observed B r 0 2 and the reaction 2 H O " + B r 0 2 + B r 0 2^B r 2 0 4 + 2 0 H " -B r 0 3 _ + B r 0 2 + H 2 0 . This claim is contrary to the results of Barkin et al (1977), and probably results from their neglect of reaction (R7). (1970) infer a considerably lower value from their experiments on the decomposition of bromite ion, and this will tend to reduce the discrepancy between calculated and experimental critical bromide ion concentrations.…”

“…The observation (Yatsimirskii et al, 1976) of C I D N P in reacting BZ reagents implicates radical mechanisms such as Processes Β and C. All observed kinetic behavior of the C e ( I I I ) -B r 0 3 system can be simulated numerically using a Process Β like mechanism (Barkin et al, 1977). The evidence in support of Process Β is extensive, albeit mainly indirect.…”

Chemiluminescent reactions in the Belousov‐Zhabotinskii oscillating system

“…difference is that, after phase 11, the rate of rise in H+ + Br-+ HOBr f Br2 + H 2 0 intensity reaches its maximum, and then declines H ularities experimentally in which the ions of various metals (Ce3+, Mn2+) are oxidized with acid bromate both in a batch reactor and in a continuous stirred tank reactor (CSTR) (Barkin et al, 1977;Geiseler andBar-Eli, 1981, Noyes and. A success of this scheme was the theoretical prediction (Bar-Eli, 1981) of the existence of self-sustained oscillations in a CSTR which were subsequently confirmed experimentally (Orban et al, 1982;Geiseler, 1982).…”

“…We have used two different sets of constants for the rate steps (Rl) -(R7): set I is based on values proposed by Field et al (1972) and modified by Barkin et al (1977) and set I1 is based on data compiled by Tyson, 1985). Recent publications (Ariese and Nagy-Ungvarai, 1986a, b;Field and Forsterling, 1986) give preference to set 11, nevertheless, we have compared the kinetic relationships with the calculated parameters of both sets of rate constants.…”

A completely inorganic oscillating system of the Belousov–Zhabotinskii type

“…Bromide ions are formed as a result of a fast reaction between Brz and hypophosphite ions. It is rather probable that both the bromide ion and bromine have the same effect on the induction time of the oxidation of Mn(I1) by bromate, as on the induction time of the oxidation of Ce(II1) by bromate [12]. It is necessary to remove by reaction (1) and also by fast BrOy--Br-reaction the produced bromine below its critical value to enable the start of reaction (1).…”