If several reactions take place simultaneously at the electrode a partial electrode
current density (c.d.)
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
,
is defined as the ratio of
to the total c.d.:
Note that
may be larger than one if cathodic and anodic reactions take place simultaneously
at the same electrode. However,
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
(in the absence of a
chemical reaction which is consecutive to the
electrode reaction and which consumes or produces species B).
is the
charge number of
electrode reaction
. Note that in the case of simultaneous electrode reactions the distribution of the
partial c.d.
may be different from that of the total c.d., i.e. the function
may be different from
.
In electroplating the term '
metal distribution' is sometimes used to designate the distribution
of the partial c.d. for metal deposition.
Source:
PAC, 1981, 53, 1827
(Nomenclature for transport phenomena in electrolytic systems)
on page 1836
