Chemistry Reference
In-Depth Information
j
j
a
j
0
+
h
j
c
E
eq
1.12
Relationship between applied over-potential and the measured
current for an electrochemical reaction.
that the charge transfer is rate determining, one refers to an activation
over-potential h
act
.
In practice, most of the electrode processes involve, besides the transport
steps, more than one stage, and often several electrons are transferred.
Suppose, for example, that a voltammetric wave is due to an electro-
chemical reaction where
n
electrons are transferred and which occurs in
n
one-electron steps:
¨
Oe
+
-
B
[1.27]
¨
Be
+
-
C
[1.28]
:
¨
Qe
+
-
S
[1.29]
¨
Se
+
-
T
[1.30]
¨
Te U
+
-
[1.31]
¨
Ze
+
-
R
[1.32]
where comparison [Equation 1.30] is supposed to be the rate-determining
step (RDS), which is preceded by
n
be
other one-electron-transfer steps and
followed by
n
af
such steps. Every step has its specific formal rate constant,
