Bray-Liebhafsky reaction

A Iodate Catalyzed Decomposition of Hydrogen Peroxide (Bray-Liebhafsky Reaction)... 

IIIA) 1979 Edelson, D., Noyes, R. M. Detailed Calculations Modeling the Oscillatory Bray-Liebhafsky Reaction, J. Phys. Chem. vol. 83, 212-220... 

III A), 1976 Sharma, K. R., Noyes, R. M. Oscillations in Chemical Systems, 13. A Detailed Molecular Mechanism for the Bray-Liebhafsky Reaction of Iodate and Hydrogen Peroxide, J. Amer. Chem. Soc. vol. 98,4345-4361... 

The Belousov-Zhabotinsky reaction is not the only one which displays oscillatory behavior. For instance the Bray-Liebhafsky reaction discovered in the 1920s by W. C. Bray and H. Liebhafsky is the decomposition of H2C>2 in O2 and H2O with I03 . 

The radical cations RI and [RI IR] generated " from RI and OH in aqueous solution are strong oxidants, and oxidize I" and Me2S at close to the encounter rate. The pulse radiolysis of HOI and IO produces HOIOH, which decomposes " to lO. At higher pH values, the conjugate base species HOIO and OIO are present. The effect of potassium iodate on the decomposition of hydrogen perioxide in the Bray-Liebhafsky reaction has been studied. " ... 

The Bray-Liebhafsky reaction is the decomposition of hydrogen peroxide into the water and oxygen in the presence of iodate and hydrogen ions ... 

IV. EXAMINATIONS OF CATALYSTS USING THE BRAY-LIEBHAFSKY REACTION AS THE MATRIX SYSTEM... 

After reading previous sections, we can conclude that the Bray-Liebhafsky reaction system, as any oscillatory one, is extremely sensitive to various perturbations, and therefore suitable for analytical applications. They can be used as the matrix for analyzing properties of the substances that already exist in the system [17,18,42,56], but also the ones that only interact with it [10-17,19-22]. Beside others, such substances can be catalysts [93,94]. 

With aim to examine catalysts by the Bray-Liebhafsky reaction system as the matrix, two examples, one in the closed and the other in the open reactor, will be given in the following. 

With the aim to compare the activities of the two mentioned catalysts (HRP and apFe) we had to examine their kinetic properties. This is performed in the Bray-Liebhafsky reaction being in the oscillatory state. The reaction was conducted in the closed well-stirred reactor. 

In this series, the catalyst and hydrogen peroxide were mixed before adding to the solution of potassium iodate and sulfuric acid, where, in analogy with other investigations, the moment when two mentioned mixtures were connected was taken as the beginning of the Bray-Liebhafsky reaction. The period of their mutual reaction Q before adding to the solution of potassium iodate and sulfuric acid was different in different experiments. AU other parameters were kept... 

By the presence of either HRP or apFe, the Bray-Liebhafsky reaction is changed in a similar manner. Some amounts of the mentioned catalysts influence decrease, whereas the other amounts influence increase of the characteristic periods Ti and Tend - In other words, some amounts of mentioned catalysts cause the acceleration of the reactions (R), (O), and (D), whereas the other amounts cause their inhibition. Anyhow, by the presence of either HRP or apFe in the BL reaction, the new reaction system for hydrogen peroxide decomposition is formed. 

In analogy with kinetic determinations of numerous substances in open reactor where the Bray-Liebhafsky reaction was used as the matrix system, we decided to analyze activity of... 

Three experimental series where temperature was the control parameter were performed under equal initial conditions. In the first series, the pure Bray-Liebhafsky reaction system was analyzed, whereas in the other two series the same system together with either catalyst A or catalyst B was considered. In the first series, the temperature was varied between 45.4 and 55.3°C, in the second series (BL system with catalyst A) between 48.2 and 58.1°C, and in the third series (BL system with catalyst B) between 45.9 and 60.0°C. 

FIGURE 8.15 The Bray-Liebhafsky reaction system without additional catalyst. (1) Time sequences with respect to temperature in °C (a) 49.5, (h) 49.9, (c) 50.2, (d) 50.7, (e) 51.0, (f) 55.3. (2) Bifurcation diagram with stable steady states (sohd circles) and envelop of large-amplitude oscillations (empty circles) and small amplitude oscillations (stars). (3) Square of oscillation amplitudes versus temperature [94]. 

Schmitz, G., Transient behaviours in the Bray-Liebhafsky reaction, in Spatial Inhomogeneities and Transient Behaviour in Chemical Kinetics, Gray, P., Nicolis, G., Baras, F., Borkmans, P., Scott, S.K., Eds., Manchester University Press, Manchester, 1990, pp. 666-668. 

Vukojevic, V., Pejic, N., Stanisavljev, D., Anic, S., and Kolar-Anic, Lj., Determination of Cl , Br , I , Mn " ", malonic acid and quercetin by perturbation of a non-equilibrium stationary state in the Bray-Liebhafsky reaction, Analyst, 124, 147-152, 1999. 

Anid, S., Mitid, D., and Kolar-Anid, Lj., The Bray-Liebhafsky reaction. I. Controlled development of oscillations, J. Serb. Chem. Soc., 50, 53-59, 1985. 

Anid, S. and Kolar-Anic, Lj., The influence of potassium iodate on hydrogen peroxide decomposition in Bray-Liebhafsky reaction, Ber. Bunsenges. Phys. Chem., 91, 1010-1013, 1987. 

Buchholtz, F.G. and Broecher, S., Oscillations of the Bray-Liebhafsky reaction of low flow rates in a continuous flow stirred-tank reactor, J. Phys. Chem. A, 102, 1556-1559, 1988. 

Anid, S., Kolar-Anid, Lj., and Koros, E., Methods to detemtine activation energies for two kinetic states of the oscillatory Bray-Liebhafsky reaction. React. Kinet. Catal. Lett., 61, 111-116, 1997. 

Sevcik, P. and Adamcikova L. Effect of a pressure decrease and stirring on oscillatory Bray-Liebhafsky reaction, Chem. Phys. Lett., 267, 307-312, 1997. 

Valent, I., Adamcikova, L., and Sevcik, P. Simulations of the iodine interphase transport effect on the oscillatory Bray-Liebhafsky reaction, J. Phys. Chem. A., 102, 7576-7579, 1998. 

Cupic, Z., Anic, S., Terlecki-Baricevic, A., and Kolar-Anic, Lj., Bray-Liebhafsky Reaction the influence of some polymers based on poly (4-vinylpyridine), React. Kinet. Catal. Lett., 54, 43-49, 1995. 

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