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Chapter 6
6.6 Write the Nernst equation for?
(a) The reduction of 0
2
?
In general terms, the Nernst equation is given by the formula:
Q
NF
RT
E
E
o
ln

=
where Q is the reaction quotient. For the reduction of oxygen:
O
2
(g) + 4 H
+
(aq) + 4 e
2 H
2
O(1)

=
=
+
+
4
2
4
2
]
[
1
log
2
059
.
0
]
[
1
H
pO
V
E
E
H
pO
Q
o
Therefore, the potential for O
2
reduction at pH = 7 and p(O
2
) = 0.20 bar is
E = 1.229 V  0.42 = 0.81 V
(b) The reduction of Fe
2
O
3
(s)?
For the reduction of solid iron(III) oxide:
Fe
2
O
3
(s) + 6 H
+
(aq) + 6 e

2 Fe(s) + 3 H
2
O(l)

=
=
+
+
6
6
]
[
1
log
6
059
.
0
]
[
1
H
V
E
E
H
Q
o
since pH = log[H
+
] = 2.3ln[H
+
] and log[H
+
]
6
= 6log[H
+
].
)
(
8
.
13
6
059
.
0
]
[
1
6
pH
V
E
E
H
Q
o

=
=
+
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View Full Document6.8 Using Frost diagrams?
(a) What happens when Cl
2
is dissolved in aqueous basic solution?
The Frost diagram for chlorine in basic solution is shown in Figure 6.16 and is
reproduced below.
If the points for Cl

and ClO
4

are connected by a straight line, Cl
2
lies above it.
Therefore, Cl
2
is thermodynamically susceptible to disproportionation to Cl

and C1O
4

when it is dissolved in aqueous base. In practice, the oxidation of ClO

is slow, so a
solution of Cl

and ClO

is formed when Cl
2
is dissolved in aqueous base.
(b) What happens when Cl
2
is dissolved in aqueous acid solution?
The Frost diagram for chlorine in acidic solution is shown in Figure 6.16. If the points for
C1

and any positive oxidation state of chlorine are connected by a straight line, the point
for Cl
2
lies below it (if only slightly). Therefore, Cl
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