Formation of BrO2 in the Belousov-Zhabotinsky-System- Investigation of the Ce3+ /BrO3
 --Reaction*

Försterling, Horst‐Dieter; Lamberz, H. J.; Schreiber, H.

doi:10.1515/zna-1980-0310

Cited by 9 publications

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“…On the basis of our ratio k2\k\ the kinetics of the Ce 3+ /Br03~-reaction may be better understood: the autocatalytic formation of Ce 4+ is slowed down if the competitive reaction (R4) is more important than assumed by FKN, and consequently the calculated Br02-concentrations must be significantly lower in accordance with our former experiments [5,6].…”

Section: Reaction (R2)supporting

confidence: 82%

“…5, full line). This proof for the occurrence of BrC>2 as an intermediate seems to be more direct than in our former experiments [4,5,6], since no corrections for the absorbance of other species were needed.…”

Section: Methodssupporting

confidence: 49%

“…8 it is to be seen, however, that this ratio is decreasing with increasing concentration c\ indicating that (R4) must be taken into account: Table 3. Maximum concentration CBr02,max, total concentration Ctot .max from (5) and ratio Ctot,max/ci as a function of the initial concentration ci of NaBr02. The values CBr02,max are taken from the least square fit in Figure 6.…”

Section: Methodsmentioning

confidence: 99%

“…Within the reaction scheme proposed by Field, Koros, and Noyes [3] (FKN-theory) this reaction is assumed to proceed in two elementary steps: In preceding experiments [4,5,6] we have been able to detect Br02 formed in this reaction. The kinetics experimentally observed was found to be in qualitative agreement with the FKN-reaction scheme.…”

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confidence: 99%

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Formation of BrO₂ in the Belousov-Zhabotinsky-System — Investigation of the HBrO₂ /BrO₃ ^–-Reaction

Försterling

Lamberz

Schreiber

1980

Zeitschrift Für Naturforschung A

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The reaction between HBr02 and bromate was studied in sulfuric acid solution. From the spectral dependence of the absorbance in the region from 400 to 600 nm it is concluded that Br02 is an intermediate of the reaction. From the maximum concentration of Br02 the equilibrium constant of the BrOa/B^O-i-equilibrium is evaluated; furthermore, a value for the ratio of the rate constants for the HBr02/Br03~-reaction and the disproportionation reaction of HBr02 is given.The autocatalytic formation of Ce 4+ is one of the essential reactions in the Belousov-Zhabotinskysystem [1,2] In preceding experiments [4,5, 6] we have been able to detect Br02 formed in this reaction. The kinetics experimentally observed was found to be in qualitative agreement with the FKN-reaction scheme. In a quantitative respect, however, the experimental results disagreed with theory; as an example, the Br02-concentrations experimentally obtained were 1/10 of the calculated values only. In order to overcome this discrepany, reaction (R2) was investigated in more detail. Experimental ProcedureSince HBr02 is not stable in acid solution, we have studied reaction (R2) by injecting NaBr02 (solved in 0.1 m NaOH) into aim solution of NaBr(>3 in 1 m sulfuric acid assuming that the reactionis much faster than all other reactions under consideration. Care was taken to use reagents of high purity. 1 m H2SO4 was prepared by dilution of conc. H2S04 (p.a. Merck) in bidistilled water. NaBrÜ3 (p.a. Fluka) was twice recrystallized from hot water. The absorption spectrum of solutions of NaBrC>3 in 1 m H2S04 changed significantly in the course of purification (Fig. 1); this fact is mainly due to the elimination of Br~-and BrO~-impurities. We were not able to reduce the residual 480 nm-absorption band by further recrystallization. NaBr02 was prepared by a modified procedure [7] basing on the synthesis described by Breiss [8]. The product was three times recrystallized from 0.1 m NaOH; the absorption spectrum given in Fig. 2 was found to be in excellent agreement with the spectra reported in [8,9]. The residual Br~-impurity of this product was estimated using the following procedure: alkaline solutions of NaBr02 (initial concentration 2.81 • 10~4 m) were injected into 1 m sulfuric acid and the absorption spectra of the reaction products were taken (Figure 3). In the case of curve 1, NaBr02 was used without further purification; in the case of curve 2, the alkaline solution of NaBr02 had been purified from Br~ by adding silver nitrate and removing the AgBr-precipitate by ultracentrifugation. The difference spectrum of curves 1 and 2 was found to agree with the spectrum of Br2 (curve 3). From the absorbance A =0.018 at X = 400 nm the Br2-concentration 1.1 • 10 -5 m was calculated (fiBr2 = 172 1 • mole-1 • cm-1 ).Assuming the reaction path 3 Br-+ HBr02 + 3 H+ -» 2 Br2 + 2 H20 the concentration of the Br~-impurity was estimat-0340-4811 I 80 / 1200-1354 $ 01.00/0. -Please order a reprint rather than making your own copy.

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Section: Reaction (R2)supporting

confidence: 82%

Section: Methodssupporting

confidence: 49%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Formation of BrO₂ in the Belousov-Zhabotinsky-System — Investigation of the HBrO₂ /BrO₃ ^–-Reaction

Försterling

Lamberz

Schreiber

1980

Zeitschrift Für Naturforschung A

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“…It turns out that the measured spectrum b) is nearly identical with the Buxton and Dainton spectrum in the wavelength range from 370 to 500 nm. In the range from 500 to 600 nm there is some significant deviation, however, although earlier spectra obtained in bromate chemistry experiments in 1 M H 2 S0 4 solution [16,22,23,24] agree with the Buxton and Dainton experiment within the limit of error. One possible explanation for the observed deviation seems to be the fact that in the experiment presented here 10 M sulfuric acid is used as a solvent, and the spectrum is changed due to the formation of (HBr0 2 ) + as suggested by Zhabotinsky [25].…”

Section: Discussionmentioning

confidence: 67%

Contribution of Malonyl Radical Control in the Classical Belousov-Zhabotinsky Reaction

Försterling

Murányi

1990

Zeitschrift Für Naturforschung A

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New strategies for studies on the kinetics and energetics of the Belousov‐Zhabotinskii reaction

Koch

Nagy-Ungvárai

1987

Ber Bunsenges Phys Chem

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Catalysis / Chemical Kinetics / Computer Experiments / Oscillatory Chemical Reactions / Thermal AnalysisThe oscillatory Belousov-Zhabotinskii reaction and its subsystems were studied by z 1700 DTA and UV experiments performed at linearly increased temperature. The starting concentrations of bromate, bromide, catalyst, and malonic acid were varied in order to obtain "concentration codes" of such series. These represent the dependence of any parameters in discrete ranges of the starting concentrations of the different components. Particularly adequate for a model check are the mechanistic codes (= MCC's), which concern the shape index and reaction type index: If these mechanistic coordinates remain constant in such a concentration interval, other data, e.g. activation energies, can be attributed to a rate-determining process. -The results led to a nine-step model which is based on the FKN mechanism and is capable of roughly reproducing the influence of the initial concentrations and heating rate on 11 parameters characteristic of the envelope and of the oscillations of the experimental signals. The MCC's of the experimental and theoretical series are similar, revealing 4-5 rate-determining steps in the different concentration ranges. -The activation energies agree with values from the literature, cited for three steps; these and further resulting activation energies are consistent with our studies with subsystems.

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Formation of BrO₂ in the Belousov-Zhabotinsky-System- Investigation of the Ce³⁺ /BrO₃ ^--Reaction*

Cited by 9 publications

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Formation of BrO₂ in the Belousov-Zhabotinsky-System — Investigation of the HBrO₂ /BrO₃ ^–-Reaction

Formation of BrO₂ in the Belousov-Zhabotinsky-System — Investigation of the HBrO₂ /BrO₃ ^–-Reaction

Contribution of Malonyl Radical Control in the Classical Belousov-Zhabotinsky Reaction

New strategies for studies on the kinetics and energetics of the Belousov‐Zhabotinskii reaction

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Formation of BrO2 in the Belousov-Zhabotinsky-System- Investigation of the Ce3+ /BrO3 --Reaction*

Cited by 9 publications

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Formation of BrO2 in the Belousov-Zhabotinsky-System — Investigation of the HBrO2 /BrO3 –-Reaction

Formation of BrO2 in the Belousov-Zhabotinsky-System — Investigation of the HBrO2 /BrO3 –-Reaction

Contribution of Malonyl Radical Control in the Classical Belousov-Zhabotinsky Reaction

New strategies for studies on the kinetics and energetics of the Belousov‐Zhabotinskii reaction

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Formation of BrO₂ in the Belousov-Zhabotinsky-System- Investigation of the Ce³⁺ /BrO₃ ^--Reaction*

Formation of BrO₂ in the Belousov-Zhabotinsky-System — Investigation of the HBrO₂ /BrO₃ ^–-Reaction

Formation of BrO₂ in the Belousov-Zhabotinsky-System — Investigation of the HBrO₂ /BrO₃ ^–-Reaction