A Raman Study of the Bromide Solutions of Zinc and Cadmium<sup>1a</sup>

Yellin, Wilbur; Plane, Robert A.

doi:10.1021/ja01472a007

Cited by 42 publications

(15 citation statements)

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“…The intermediate coordination ͓͑ZnBr 2 ͑OH 2 ͒ 2 ͔ 0 ͒ was also found. [10][11][12][13] Regarding the exact geometry of the coordination of the Zn 2ϩ ions, there is evidence for tetrahedral coordination 6,[8][9][10][11][12][13][14][15][16] as well as for octahedral coordination. 6,8 Another question is, if the coordinated Zn 2ϩ ions exist as distinct entities, or whether they are linked together to polymer species, i.e., chains of coordinated Zn 2ϩ ions that are held together by the fact that neighbouring Zn 2ϩ ions share one or even more ligands.…”

Section: Introductionmentioning

confidence: 99%

Static and dynamic structural analysis of a saturated solution of ZnBr2 in water: Anomalous x-ray diffraction and molecular dynamics simulations

Löffler

Mager

Gerner

et al. 1996

The Journal of Chemical Physics

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Articles you may be interested inThe solvation of Cl−, Br−, and I− in acetonitrile clusters: Photoelectron spectroscopy and molecular dynamics simulations Constant pressure molecular dynamics simulations of the dodecamers: d(GCGCGCGCGCGC)2 and r(GCGCGCGCGCGC)2 Structure and dynamics of undercooled and glassy aqueous ionic solutions by NMR, Xray and neutron scattering AIP Conf.The supposedly very simple system of a saturated solution of ZnBr 2 in water exhibits unusually complex and therefore interesting structural behavior. Motivated by this, Mager did a detailed x-ray diffraction study ͑Th. Mager, PhD. thesis, Universität Würzburg, 1991͒, and we performed a long molecular dynamics ͑MD͒ simulation-using potential parameters from the general purpose GROMOS force field-of such a solution, which can be grossly characterized by the formula ZnBr 2 •3H 2 O. We start by calculating those properties that are directly accessible through the experiment from the MD simulation, in order to validate the physical relevance of the simulation. Seeing that the simulation delivers results that are compatible with those of the experiment, we proceed by analyzing the MD simulation in much more detail according to the static and dynamic structure of the system, thereby gaining insight into the structural behavior of ZnBr 2 •3H 2 O that is very difficult, if at all possible, to get from experimental studies. To this end we use the Voronoi algorithm to define coordination shells around atoms and ions in ZnBr 2 •3H 2 O. We study the time averaged as well as the time-resolved geometry and composition of these coordination shells and find that octahedral coordination of Zn 2ϩ ions is the dominant geometry in ZnBr 2 •3H 2 O, and that these octahedra are remarkably stable ͑after 1 ns only 10% decayed͒. We further find evidence for polymerlike Zn 2ϩ chains, where O atoms of water and Br Ϫ ions connect the Zn 2ϩ ions.

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Section: Introductionmentioning

confidence: 99%

Static and dynamic structural analysis of a saturated solution of ZnBr2 in water: Anomalous x-ray diffraction and molecular dynamics simulations

Löffler

Mager

Gerner

et al. 1996

The Journal of Chemical Physics

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“…7a (18). This is due to the well-known autocomplexation that o'ccurs in zinc halide solutions as indicated by EMF, thermal and Raman spectroscopic experiments (18,23,28). Thus, Shchukarev et al (29) reported widely different TAS values for the formation of ZnBr § ZnBr2, ZnBr3-, and ZnBr42-complex ions.…”

Section: Discussionmentioning

confidence: 98%

Electrochemical Calorimetry of the Zinc and Bromine Electrodes in Zinc‐Bromine and Zinc‐Air Batteries

Donepudi

Conway

1984

J. Electrochem. Soc.

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Direct calorimetric measurements are reported on three half-cell reactions of interest in zinc battery thermodynamics: the Zn/Zn 2+ reaction in aqueous Br-solution; the BrJBr-reaction at Pt and the Zn/ZnO-ZnO~-reaction in alkali. An experimental procedure is described for determining the single reaction heats, observable as TAS quantities, in both directions of the above reactions, thus providing a method for eliminating, by difference, the Joule heating effects which are unavoidable in the course of measurements at finite currents. Corrections for entropies of transport are made and discussed. Under certain conditions, where Zn corrosion can occur with evolution of H2, the TAS heat change for that process is also determinable. Some heat changes for overall cell reactions are also determined~ While enthalpy changes for reversible electrochemical reactions can be obtained from EMF measurements and their temperature coefficients by means of the Nernst equation through the Gibbs-Helmholtz relation, such values are necessarily for the overall, two-electrode reaction. Direct calorimetric measurements, subject to some corrections for ionic entropies of transport, can be applied to evaluation of the heat changes that are associated with the electrochemical reactions at the electrodes of a cell. Such directly measurable heats are, however, associated with the "TAS" quantity for the cell reaction, rather than the AH.It is of interest to recall that the actual enthalpy change, AH, for an electrode reaction is not measurable calorimetrically like it would be for a corresponding overall chemical reaction. This is because the AH normally constitutes the main component of the AG value determining the EMF of the cell. From measurements of the latter at various temperatures, ~ can, of course, be determined using a form of the Gibbs-Helmholtz equation.Direct calorimetric measurements made at a suitably designed electrode configuration with an appropriately arranged thermal detection probe, and separated anode and cathode compartments, can also give information on the TZkS quantity for single electrode processes which are of interest in a general way in electrochemical thermodynamics and ionic solution electrochemistry. In some papers (1-3), these TAS quantities have been referred to as electrolytic Peltier heats, and values for several redox reactions at electrodes have been reported (4-5). The first reliable work of this kind was done by Lange and Hesse (6) and Lange and Monheim (7) some years ago, but, for many years since that time up until several years ago, few other papers have appeared on this topic.Renewed interest in electrochemical calorimetry has arisen on account of the importance of measurements of overall and component heat changes in battery processes. Such measurements are essential for understanding the thermochemistry of battery reactions and in assessing practical energy efficiencies as well as evaluating heat changes associated with various contributions to irreversibility in battery charge and discharge cycle...

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“…This corresponds to the work of Morris et al 34 who found that a peak at 172 cm -1 corresponded to the ZnBr 4 2species. The peak at 205 cm -1 has been correlated with the ZnBr 2 species by both Morris et al 34 and Delaulle et al 35 However, Yellin et al 36 correlate the peak seen at 205 cm -1 with the ZnBr + species. The peak at 185 cm -1 is assigned to the species ZnBr 3 by both Delaulle et al 35 and Morris et al 34 From the above literature comparisons, the peaks obtained in this study for the Zn-Br species were assigned the following wave numbers: Figure 11 is interesting.…”

Section: Structure Of Concentrated Zinc Halide Solutionsmentioning

confidence: 91%

Kinetic, Solution, and Interfacial Aspects of Iron Corrosion in Heavy Brine Solutions

Smart¹,

Bhardwaj²,

Bockris³

1992

CORROSION

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The corrosion rates of iron at temperatures between 60 and 120°C have been determined in very concentrated zinc halide solutions. The effects of calcium halide were investigated. The corrosion rates were lower in bromidecontaining solutions than in chloride solutions. On the other hand, lower corrosion rates were observed with calciumcontaining halides solutions than in zinc halide solutions. In zinc halide solutions, the cathodic reaction is under diffusion control with higher currents obtained with the chloride solutions. The nature of complexation in the zinc halide solutions is discussed in detail. The structure of the hydrogen bonding in the water was greatly decreased in the presence of the halides, and a maximum decrease in hydrogenbonded species appeared to take place in the presence of calcium halide solutions. The structure of the iron interface was determined after immersion of iron in concentrated zinc halide solutions at 120°C for two weeks. In pure zinc chloride solutions, the surface became covered with zinc hydroxide. In calcium chloride + zinc chloride solution and zinc bromide solution, a large amount of Fe 2 O 3 was identified on the sample surface.

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A Raman Study of the Bromide Solutions of Zinc and Cadmium^1a

Cited by 42 publications

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Static and dynamic structural analysis of a saturated solution of ZnBr2 in water: Anomalous x-ray diffraction and molecular dynamics simulations

Static and dynamic structural analysis of a saturated solution of ZnBr2 in water: Anomalous x-ray diffraction and molecular dynamics simulations

Electrochemical Calorimetry of the Zinc and Bromine Electrodes in Zinc‐Bromine and Zinc‐Air Batteries

Kinetic, Solution, and Interfacial Aspects of Iron Corrosion in Heavy Brine Solutions

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A Raman Study of the Bromide Solutions of Zinc and Cadmium1a

Cited by 42 publications

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Static and dynamic structural analysis of a saturated solution of ZnBr2 in water: Anomalous x-ray diffraction and molecular dynamics simulations

Static and dynamic structural analysis of a saturated solution of ZnBr2 in water: Anomalous x-ray diffraction and molecular dynamics simulations

Electrochemical Calorimetry of the Zinc and Bromine Electrodes in Zinc‐Bromine and Zinc‐Air Batteries

Kinetic, Solution, and Interfacial Aspects of Iron Corrosion in Heavy Brine Solutions

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A Raman Study of the Bromide Solutions of Zinc and Cadmium^1a