Chemistry Reference
In-Depth Information
10
5
10
4
10
3
10
2
8.0
9.0
10.0
11.0
12.0
13.0
pH
Figure 6.41.
Rate constants versus pH for ferrate(V) reaction with EDTA (adapted
from Noorhasan et al. [385] with permission of Elsvier Inc.).
in the studied pH range of the kinetic measurements (Table 6.8). The fractions
of the species are presented in Figure 6.38. Of the possible 20 reactions between
the species of ferrate(VI) and EDTA, only 6 reactions successfully fit the data
over the entire pH range using the model in Equation (6.142) (a solid line in
Fig. 6.35). The six reactions and their calculated individual rate constants are
given in Equations (6.145)-(6.150):
+
−
5
H FeO H Y
+
→
Fe III
(
)
+
products
k
=
3 30 0 12 10
.
±
.
×
/M/s
(6.145)
3
4
3
155
2
−
4
H FeO H Y
+
→
Fe III
(
)
+
products
k
=
1 18 0 09 10
.
±
.
×
/M/s
(6.146)
2
4
2
156
−
2
−
2
HFeO H Y
+
→
Fe III
(
)
+
products
k
=
2 73 0 50 10
.
±
.
×
/M/s
(6.147)
4
2
157
−
3
−
1
HFeO HY
+
→
Fe III
(
)
+
products
k
=
6 71 0 17 10
.
±
.
×
/M/s
(6.148)
4
158
2
−
3
−
−
1
FeO
+
HY
→
Fe III
(
)
+
products
k
=
6 88 0 19 10
.
±
.
×
/M/s
(6.149)
159
2
−
4
−
−
2
FeO
+
Y
→
Fe III
(
)
+
products
k
=
8 00 0 50 10
.
±
.
×
/M/s
.
(6.150)
160
In the reaction of ferrate(V) with EDTA,
HFeO
2−
and
FeO
3−
can react with
two forms of EDTA in the studied pH range (Eqs. 6.151-6.154):
HFeO
2
−
+
HEDTA
3
−
→
products
k
=
1 18 0 12 10
.
±
.
×
4
/M/s
(6.151)
4
161
FeO
3
−
+
HEDTA
3
−
→
products
k
=
2 85 0 29 10
.
±
.
×
4
/M/s
(6.152)
4
162
HFeO
2
−
+
EDTA
4
−
→
products
k
=
3 58 0 36 10
.
±
.
×
4
/M/s
(6.153)
4
163
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