ISSN:
1572-8838
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Electrical Engineering, Measurement and Control Technology
Notes:
Abstract The reaction Cl2+2e ⇔ 2Cl− has been studied by transient electrochemical techniques on a vitreous carbon electrode in fused alkali chlorides. Two regimes have been detected: for small overpotentials the electrode response obeys the classical laws of linear diffusion, for larger overpotentials the electrode behaviour involves the gas coming from the bubbles. A model is presented to describe these mechanisms. Four steps are considered: dissolution of chlorine around a gas bubble, diffusion in the electrolyte, charge transfer and chloride ion migration. The first step is always rapid. The influence of the three other steps is examined. It is indicated that the largest part of the reaction occurs near the triple contact interface. At the very extremity of the tip, charge transfer is the primary limiting factor: it is considered that over a distance of a few atomic diameters the mass transport is very rapid. At the largest distances the diffusion of dissolved chlorine constitutes the main limiting factor. The ohmic drop due to the electrical resistance of the electrolyte remains small. The influence of the interfacial tension and of the shape of the bubbles are predicted. The non-stationary situation is also examined in order to take into account the size variation of the gas bubbles during transient conditions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01320639
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