Journal Archive Collections

Permanent URI for this communityhttp://localhost:4000/handle/123456789/16937

Browse

Has files: YesSubject: search.filters.subject.Electrochemistry

Search Results

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Coupled Fluxes in Electrochemistry Concentration Distributions near Electrodialysis Membranes
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (09-12), 1978) Brady, John F.; Turner, J. C. Robin
    In electrodialysis the gradient of electrical potential leads to coupling of the flux equations for all the different ionic species. When these ions have the same (numerical) valency, their concentrations close to and within the electrodialysis membrane can be obtained from a closed-form solution, as can the potential. When they do not, a series solution is derived, which requires that all the ionic fluxes be known. If they are not available (e.g. from measurement) they must be guessed at the start of an iterative scheme. Concentration and potential profiles are discussed for cases with and without “water-splitting”, which is the production of sizeable fluxes of H+ and OH– ions even though the feed solution is effectively neutral. The concept of “limiting current density” is discussed, and is shown to lose much of its usefulness in the presence of water-splitting.
  • No Thumbnail Available
    Item
    Electric Modulated Reflectance at Mercury Electrodes: Transition between Electrostatic Adsorption and Chemisorption
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (10), 1974) Gottesfeld, Shimshon; Conway, Brian E.
    Reflectance changes at polished electrode surfaces can arise from changes of optical properties of the metal surface and from changes of local ionic concentrations in the double-layer. The significance of these two effects in the interpretation of overall reflectance changes with potential (“electro-reflectance” effects), in the absence of film formation due to oxidation of the metal, is examined for the case of a mercury electrode. A liquid Hg surface is, however, unsatisfactory as a mirror electrode due to electro-mechanical oscillations which cause spurious reflectance changes. A thin Hg film on top of an electrolytically amalgamated Pt surface gives excellent results. The transition between electrostatic double-layer adsorption effects and more specific chemisorption can be demonstrated optically in the reflectance behaviour associated with Cl– and I– adsorption, by examination of reflectance of perpendicular and parallel polarized light in conjunction with phase-sensitive detection measurements. The behaviour of adsorbed thiourea is compared with that of the two halide ions.
  • No Thumbnail Available
    Item
    The Oxygen Electrode: Part 3,—Inhibition of the Oxygen Evolution Reaction
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (6), 1972) Burke, L. D.; McCarthy, F.; O’Meara, T. O.
    The anodic behaviour of water is discussed in terms of a model in which discharge occurs via a cation radical intermediate which rapidly loses a proton to yield potential-determining hydroxyl radicals on the metal surface. Hysteresis in the charging curves in the case of noble metal electrodes is explained in terms of an anodic stage involving the production of these hydroxyl radicals on the surface, and a subsequent cathodic stage involving (largely) the reduction of a layer of chemisorbed oxygen. Coverage of the electrode surface by hydroxide radicals is not at any time regarded as being very large as conversion to an oxide film occurs, possibly via a peroxide intermediate. Oxygen evolution is assumed to occur via a similar mechanism, the adsorbed peroxide intermediate being undetectable under normal conditions as peroxides arc instantaneously oxidized in the potential region in question. An attempt is made to account for the mechanism proposed for oxygen evolution, and other facets of oxygen electrochemistry, in terms of solvent electrostriction at the metalsolution interface at high positive potentials.
  • No Thumbnail Available
    Item
    Effect of the Solution Vapour Pressure on the Temperature Dependence of the Dissociation Constant of Acetic Acid in Water
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (10), 1972) Lown, D. A.; Thirsk, H. R.
    The dissociation constant of acetic acid in water is between 4 and 26% greater at the solution vapour pressure than at one atmosphere in the range 250 to 374°C. K = /(T)s.v.P. corresponds to neither the isobaric nor isochoric conditions, and the error introduced by neglecting the effect of the vapour pressure on the equilibrium at high temperatures is discussed.