Chemistry Reference
In-Depth Information
5.5
y
= 0.9776x + 3.1146
R
2
= 0.9922
4
5.0
4.5
y
= 0.9876x + 2.2076
R
2
= 0.9974
3
4.0
3.5
2
y
= 0.9742x + 1.2882
R
2
= 0.9984
3.0
2.5
y
= 0.9883x + 0.3114
R
2
= 0.9983
1
2.0
1.5
1.3
1.5
1.7
1.9
2.1
Log
d
(mm)
9.7
Logarithmic plot of the impedance at zero phase-angle shift as a
function of distance between the electrode (
d
) obtained from
the electrochemical cell with
A
=
490.6 mm
2
,
T
=
298.0 K and an
electrolyte concentration of (1) 1
¥
10
-
1
, (2) 1
¥
10
-
2
, (3) 1
¥
10
-
3
and
(4) 1
¥
10
-
4
mol l
-
1
.
between the electrodes. Therefore, Equation 9.3 can be modified by imple-
mentation of a new factor (
k
3
) and taking into account the relationship
obtained in Fig. 9.7:
RkdA c
=
-
068
.
-
1
[9.5]
3
with k
3
a factor which is independent of
A
,
d
and
c
, and
d
being the dis-
tance between the electrodes. Equation 9.6 shows the interrelationships
between the different factors used:
kkA
=
-
068
.
=
kA d
-
068
.
[9.6]
1
2
3
and
kkd
2
=
[9.7]
3
Using Equations 9.6 and 9.7, it is possible to calculate the values for
k
1
,
k
2
and
k
3
for different values of
A
,
d
and
c
, and the values for
k
2
and
k
1
pre-
viously obtained can be verified. These values are given in bold in Tables
9.2 and 9.3 and can be compared with the values obtained in the previous
sections. From the data shown in Fig. 9.7, a value for
k
3
of 9.5 ± 0.3 is
obtained. With this value, it is possible to calculate
k
2
as a function of dis-
tance between the electrodes according to Equation 9.7, and these results
