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8.0
7.0
6.0
HSO
3
-
NO
2
-
5.0
Fe
2+
Mn
2+
4.0
H
2
O
2
3.0
2.0
Cl
-
1.0
0.0
0.5
1.0
1.5
2.0
2.5
E
o
(V)
Figure 6.25.
log
k
(FeO
2+
) as a function of the standard 1 − e
−
reduction potential (
E
o
)
for the electron transfer reaction of FeO
2+
with inorganic compounds. (
) Literature
values (the point for
NO
−
also includes HNO
2
) (adapted from Jacobsen et al. [321]
with the permission of Wiley, Inc.).
TABLE 6.4. Reactivity of Ferryl Ion and Fe(IV) Pyrophosphate Complex with
Inorganic Ions
ΔH
‡
, kJ/mol
ΔS
‡
, J/mol Metal(II)
Compound
k
, /M/s 25°C
k
, /M/s 25°C
Fe
IV
O
2+
(pH 1.0)
[(P
2
O
7
)
2
Fe
IV
O]
6−
(pH 10.0)
HNO
2
1.1 × 10
4
32.0
−60.1
Mn
2+
1.2 × 10
6
≤10
5
-
Fe
2+
1.6 × 10
6
NO
−
Cl
−
1.0 × 10
2
-
Co
2+
5.5 × 10
5
2.5 × 10
5
-
Ni
2+
<4.0 × 10
2
HSO
−
4.5 × 10
5
Cu
2+
<4.0 × 10
6
SO
2
-
Mn
2+
1.0 × 10
4
18.8
−105.2
Fe
2+
1.8 × 10
5
4.5
−136.8
Data taken from References 321, 326, and 358).
‡
Activation parameter.
The reaction between Fe
2+
with the ferryl ion was studied at an initial ratio
of [Fe
2+
]/[O
3
] > 3 (Eq. 6.94):
2
+
2
+
3
+
−
5
FeO
+
Fe
+
H O Fe
→
+
2
OH
k
=
8 5 10
.
×
/M/s
.
(6.94)
2
104
In this reaction, an iron(III) dimer was observed as an intermediate; the
yield of which was temperature dependent [326]. The results suggest reaction
(6.94) can be branched into reactions (6.95a) and (6.95b):
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