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Byju's Answer
Standard XII
Chemistry
Hess' Law
KCls⟶ K + + C...
Question
K
C
l
(
s
)
⟶
K
+
+
C
l
−
The heat evolved in kcal for the process at
250
∘
C
of dissolving 1.0 mole of KCl in excess of water is __________.
[Given:
Δ
H
∘
f
of
K
+
(
a
q
)
,
C
l
−
(
a
q
)
and
K
C
l
(
s
)
are -60, -40 and -104 kcal/mole]
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Solution
The heat evolved for the process is
Δ
H
=
Δ
H
f
(
K
+
)
+
Δ
H
f
(
C
l
−
)
−
Δ
H
f
(
K
C
l
)
=
−
60
k
c
a
l
/
m
o
l
−
40
k
c
a
l
/
m
o
l
−
(
−
104
k
c
a
l
/
m
o
l
)
=
4
k
c
a
l
/
m
o
l
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Similar questions
Q.
A solution containing
0.5
g
of
K
C
l
dissolved in
100
g
of water and freezes at
0.24
o
C
. Calculate the degree of dissociation of the salt. (
K
f
for water
=
1.86
o
C
. Atomic weights [
K
=
39
,
C
l
=
35.5
].
Q.
K
C
l
O
4
is obtained from the following sequence of reactions:
C
l
2
+
2
K
O
H
→
K
C
l
+
K
C
l
O
+
H
2
O
3
K
C
l
O
→
2
K
C
l
+
K
C
l
O
3
4
K
C
l
O
3
→
K
C
l
+
3
K
C
l
O
4
.
The correct statement among the following is/are
Q.
H
2
+
1
/
2
O
2
⟶
H
2
O
;
Δ
H
⊖
=
−
68
K
c
a
l
.
K
+
H
2
O
+
a
q
⟶
K
O
H
(
a
q
)
+
1
/
2
H
2
;
Δ
H
⊖
=
−
48
K
c
a
l
.
K
O
H
+
a
q
⟶
K
O
H
(
a
q
)
;
Δ
H
⊖
=
−
14
K
c
a
l
From the above data, the standard heat of formation of
K
O
H
i
n
K
c
a
l
is
Q.
The heat of formation of
C
2
H
5
O
H
(
l
)
is -66 kcal/mole. The heat of combustion of
C
H
3
O
C
H
3
(
g
)
is -348 kcal mole,
Δ
H
f
for
H
2
O
and
C
O
2
are - 68 kcal/mole and -94 kcal/mole respectively. Then determine the
Δ
H
for the isomerisation reaction
C
2
H
5
O
C
H
3
(
g
)
, and
Δ
E
for the same are at T = 25
∘
C
Q.
What will be the product for the reaction given below?
KCl + Na
⇒
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