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Byju's Answer
Standard XII
Chemistry
Spontaneity
Calculate, th...
Question
Calculate, the
Δ
H
at
85
o
C
for the reaction:
F
e
2
O
3
(
s
)
+
3
H
2
⟶
2
F
e
(
s
)
+
3
H
2
O
(
l
)
The data are:
Δ
H
o
298
=
−
33.29
k
J
/
m
o
l
and
Substance
F
e
2
O
3
(
s
)
F
e
(
s
)
H
2
O
(
l
)
H
2
(
g
)
C
o
P
(
J
/
K
m
o
l
)
103.8
25.1
75.3
28.8
Open in App
Solution
F
e
2
O
3
(
s
)
+
3
H
2
⟶
2
F
e
(
s
)
+
3
H
2
O
(
l
)
Δ
C
P
=
(
C
P
)
P
−
(
C
P
)
R
=
(
2
×
25.1
+
3
±
75.3
)
−
(
103.8
+
3
×
28.8
)
=
85.9
J
Δ
H
T
2
−
Δ
H
T
1
T
2
−
T
1
=
Δ
C
P
Δ
H
358
−
(
−
33.29
)
358
−
298
=
85.9
×
10
−
3
Δ
H
358
=
−
28.14
k
J
/
m
o
l
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1
Similar questions
Q.
Calculate
Δ
H
at
358
K
for the reaction,
F
e
2
O
3
(
s
)
+
3
H
2
(
g
)
→
2
F
e
(
s
)
+
3
H
2
O
(
l
)
Given that ,
Δ
H
298
=
−
33.29
k
J
m
o
l
−
1
and
C
P
f
o
r
F
e
2
O
3
(
s
)
,
F
e
(
s
)
,
H
2
O
(
l
)
and
H
2
(
g
)
are
103.8
,
25.1
,
75.3
,
a
n
d
28.8
J
/
K
m
o
l
.
Q.
The standard enthalpy of formation of
H
2
O
(
l
)
and
F
e
2
O
3
(
s
)
are respectively
−
286
k
J
m
o
l
−
1
and
−
824
k
J
m
o
l
−
1
. What is the standard enthalpy change for the following reaction?
F
e
2
O
3
(
s
)
+
3
H
2
(
g
)
⟶
3
H
2
O
(
l
)
+
2
F
e
(
s
)
Q.
For reduction of ferric oxide by hydrogen,
F
e
2
O
3
(
s
)
+
3
H
2
(
g
)
→
2
F
e
(
s
)
+
3
H
2
O
(
l
)
:
Δ
H
o
300
=
−
26.72
k
J
. The reaction was found to be too exothermic. To be convenient. it is desirable that
Δ
H
o
should be at the most - 26 kJ . At what temperature difference it is possible ?
C
p
[
F
e
2
O
3
]
=
105
,
C
p
[
F
e
(
s
)
]
=
25
,
C
p
[
H
2
O
(
l
)
]
=
75
,
C
p
[
H
2
(
g
)
]
=
30
(
all are in J/mol
)
Q.
From the following data at 25C, Calculate the standard enthalpy of formation of FeO(s) and of
F
e
2
O
3
(
s
)
.
Reaction
Δ
r
H
(
K
J
/
m
o
l
e
)
(1)
F
e
2
O
3
(
s
)
+
3
C
(
g
r
a
p
h
i
t
e
)
→
2
F
e
(
s
)
+
C
O
(
g
)
492
(2)
F
e
O
(
s
)
+
C
(
g
r
a
p
h
i
t
e
)
→
F
e
(
s
)
+
C
O
(
g
)
155
(3)
C
(
g
r
a
p
h
i
t
e
)
+
O
2
(
g
)
→
C
O
2
(
g
)
-393
(4)
C
O
(
g
)
+
1
/
2
O
2
(
g
)
→
C
O
2
(
g
)
-282
Q.
Given that:
2
F
e
(
s
)
+
3
2
O
2
(
g
)
⟶
F
e
2
O
3
(
s
)
;
Δ
H
=
−
193.4
k
J
.
.
.
(
i
)
M
g
(
s
)
+
1
2
O
2
(
g
)
⟶
M
g
O
(
s
)
;
Δ
H
=
−
140.2
k
J
.
.
.
.
(
i
i
)
What is
Δ
H
of the reaction?
3
M
g
+
F
e
2
O
3
⟶
3
M
g
O
+
2
F
e
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