AbstractsChemistry

Studies in electrochemistry. : Part I. Dropping amalgam electrodes. Part II. Copper deposition in a convention-free system.

by Robert Chapman. Turner




Institution: McGill University
Department: Department of Chemistry.
Degree: PhD
Year: 1951
Keywords: Chemistry.
Record ID: 1543772
Full text PDF: http://digitool.library.mcgill.ca/thesisfile124083.pdf


Abstract

The polarographic method of chemical analysis was introduced by Professor J. Heyrovsky in a series of papers published between 1922 and 1926. The method is based on interpretation of current-potential curves obtained when electroreducible or electro-oxidizable substances are reduced or oxidized at a dropping mercury electrode. The complete cell consists of a dropping mercury electrode, and another electrode which is essentially non-polarizable. The curve obtained by plotting the external voltage applied to the cell against the resulting current is the current-voltage curve, and since the one electrode is non-polarizable, this curve is actually the current-potential curve of the dropping electrode. Polarographic analysis depends essentially on certain unique characteristics of these current-potential curves. In an electrolytic cell which consists of a flat mercury electrode in combination with an electrode of constant potential, the reaction which takes place at the mercury electrode may be either reduction or oxidation depending on the direction of the current. If the reaction is reduction of metal ions to the corresponding metal, the metal may be soluble or insoluble in the mercury. Only the latter case, that is, the reduction of positive ions to metals soluble in mercury need be considered here. Such a reaction is illustrated by the equation Hg + Mz+ + ze = MHg [...]