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current efficiency

Also contains definition of: metal distribution

If several reactions take place simultaneously at the electrode a partial electrode current density (c.d.) j k can be assigned to each reaction. It is given by the stoichiometry of the reaction and by the amount of substance of B reacting (per unit time and per unit electrode area) in the reaction considered. The current efficiency of reaction k, ɛ k is defined as the ratio of j k to the total c.d.:
ɛ k = j k ∑ m j m
Note that ɛ k may be larger than one if cathodic and anodic reactions take place simultaneously at the same electrode. However, ɛ k still gives correctly the product yield, which is the quantity of industrial interest. The product yield is the amount of substance of B produced per unit charge and is equal to ɛ k ν B , k n k F (in the absence of a chemical reaction which is consecutive to the electrode reaction and which consumes or produces species B). n k is the charge number of electrode reaction k. Note that in the case of simultaneous electrode reactions the distribution of the partial c.d. j k may be different from that of the total c.d., i.e. the function j k x j = f k x may be different from j x j = f x. In electroplating the term 'metal distribution' is sometimes used to designate the distribution f k x of the partial c.d. for metal deposition.
PAC, 1981, 53, 1827 (Nomenclature for transport phenomena in electrolytic systems) on page 1836
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IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.
Last update: 2014-02-24; version: 2.3.3.
DOI of this term: doi:10.1351/goldbook.C01458.
Original PDF version: http://www.iupac.org/goldbook/C01458.pdf. The PDF version is out of date and is provided for reference purposes only. For some entries, the PDF version may be unavailable.
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