Platinum as a HOI/I Redox Electrode and Its Mixed Potential in the Oscillatory Briggs-Rauscher Reaction.

Pt is a common redox electrode used to follow oscillations qualitatively in the Briggs-Rauscher (BR) and the Bray-Liebhafsky (BL) reactions from the time of their discovery. Although the potential oscillations of the electrode reflect the temporal pattern of the reaction properly, there is no general agreement as to how that potential is determined by the components of the reaction mixture. In this article, first we investigate how iodine species in different oxidation states affect the potential of a Pt electrode.

HOI versus HOIO selectivity of a molten-type AgI electrode.

Unlabelled: AgI electrode is often applied not only to determine iodine concentration but also to follow oscillations in the weakly acidic medium of the Bray-Liebhafsky and Briggs-Rauscher reactions where it partly follows the hypoiodous acid (HOI) concentration. It is known that HOI attacks its matrix in the corrosion reaction: AgI + HOI + H(+) ⇆ Ag(+) + I2 + H2O and the AgI electrode measures the silver ion concentration produced in that reaction. The signal of the electrode can be the basis of sensitive and selective HOI concentration measurements only supposing that an analogous corrosive reaction between AgI and iodous acid (HOIO) can be neglected.

Kinetics of the iodate reduction by hydrogen peroxide and relation with the Briggs-Rauscher and Bray-Liebhafsky oscillating reactions.

The iodate reduction by hydrogen peroxide in acidic solutions is part of the Bray-Liebhafsky and Briggs-Rauscher oscillating reactions. At low hydrogen peroxide concentrations, typical of the Bray-Liebhafsky reaction, its rate law is -d[IO(-)(3)]/dt = (k'(R) + k"(R)[H(+)])[IO(-)(3)][H(2)O(2)] with k'(R) = 1.3 × 10(-7)(20°), 7.

Iodine oxidation by hydrogen peroxide and Bray-Liebhafsky oscillating reaction: effect of the temperature.

This work presents a new experimental kinetic study at 39° and 50° of the iodine oxidation by hydrogen peroxide. The results allow us to obtain the temperature effect on the rate constants previously proposed at 25° for our model of the Bray-Liebhafsky oscillating reaction (G. Schmitz, Phys.

Iodine oxidation by hydrogen peroxide in acidic solutions, Bray-Liebhafsky reaction and other related reactions.

The kinetics of the iodine oxidation by hydrogen peroxide is a complicated function of the concentrations of iodine, hydrogen peroxide, perchloric acid and iodate. A proposed model in eight steps explains the new experimental results. It explains also the effect of the concentrations at the steady state of the hydrogen peroxide decomposition catalyzed by iodine and iodate.

Stoichiometric network analysis and associated dimensionless kinetic equations. Application to a model of the Bray-Liebhafsky reaction.

The stoichiometric network analysis (SNA) introduced by B. L. Clarke is applied to a simplified model of the complex oscillating Bray-Liebhafsky reaction under batch conditions, which was not examined by this method earlier.

Complex and chaotic oscillations in a model for the catalytic hydrogen peroxide decomposition under open reactor conditions.

Numerous periodic and aperiodic dynamic states obtained in a model for hydrogen peroxide decomposition in the presence of iodate and hydrogen ions (the Bray-Liebhafsky reaction) realized in an open reactor (CSTR), where the flow rate was the control parameter, have been investigated numerically. Between two Hopf bifurcation points, different simple and complex oscillations and different routes to chaos were observed. In the region of the mixed-mode evolution of the system, the transitions between two successive mixed-mode simple states are realized by period-doubling of the initial state leading to a chaotic window in which the next dynamic state emerges mixed with the initial one.