Polarographic Theory, Instrumentation, and Methodology

Hume, David N.

doi:10.1021/ac60185a018

Cited by 4 publications

(1 citation statement)

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“…Possibly, the most useful methods for determining the electrochemical behavior of substances are polarography (117)(118)(119) and voltammetry (120). The International Union of Pure and Applied Chemistry (IUPAC) recommends that "polarography" and "voltammetry" be restricted to mean methods that involve varying-area and fixed-area electrodes, respectively (121), a distinction not always made. Polarography is an especially attractive tool for the study of radioactive substances because the worker and apparatus can be shielded easily from the radioactive material and because very small volumes of samples that contain substances in very low concentrations can be studied (122).…”

Section: Electrochemical Behavior Of Substancesmentioning

confidence: 99%

Radioelectrochemistry. Review

Raaen¹

1974

Anal. Chem.

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In part I of this report, we described chronocoulometric measurements of lead iodide and bromide adsorptions in which discontinuities in adsorption isotherms were related to surface solubility properties of the lead halide salts. While it is tempting to try to relate those abrupt changes in Fpb to the abrupt occurrences of inhibition observed in Part II, we believe this would be an error. We regard the two sets of observations as representing two different transitions for the adsorbed lead species. It is unfortunately not possible, for solubility (of Hg(II) halides) reasons, to conduct the inhibition tests in solutions of composition yielding adsorption isotherm discontinuities. We do know, however, from data in 1.0M I* and Br" obtained in this and a preceding report (3) that no large change in Pb occurs over the inhibition transition interval for Hg(II) reduction, and that Pb is furthermore close in value to the limiting plateau Pb of adsorption isotherm in Figures 1 and 2. The inhibition results appear to tell us that at least bits and traces of further lead halide adsorption can occur beyond formation of the two-dimensional PbX2 crystal at the adsorption isotherm, which is to say that the initially formed surface phase must not represent a "perfect crystal.'' The imperfections may be small boundary openings between patches of surface crystal, intruding adsorbed halide, or possibilities for structural reorganizations which can be eliminated or accomplished, by small amounts of additional lead halide. Whatever the reason, the rather readily penetrable surface crystal formed at the adsorption isotherm discontinuity is transformed into a surface phase exceedingly impenetrable from either the solution or electrode side by species other than the Pb(II) ion itself. In the case of Pb(II), actual penetration of intact surface phase is, of course, not required since Pb(II) can pass the surface lattice by simple exchange.

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Section: Electrochemical Behavior Of Substancesmentioning

confidence: 99%