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Byju's Answer
Standard XII
Chemistry
Heat of Formation
On the basis ...
Question
On the basis of the following thermochemical data:
(
Δ
f
G
0
(
H
)
+
(
a
q
)
=
0
)
H
2
O
(
l
)
⟶
H
+
(
a
q
)
+
O
H
−
(
a
q
)
;
Δ
H
=
57.32
k
J
H
2
(
g
)
+
1
2
O
2
(
g
)
⟶
H
2
O
(
l
)
;
Δ
H
=
−
286.20
k
J
The value of enthalpy of formation of
O
H
−
ion at
25
o
C
is:
A
−
228.51
k
J
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B
−
198.51
k
J
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C
+
238.5
k
J
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D
−
238.5
k
J
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Solution
The correct option is
B
−
228.51
k
J
Solution:- (A)
−
228.88
k
J
Given:-
H
2
O
(
l
)
⟶
H
+
(
a
q
.
)
+
O
H
−
(
a
q
.
)
Δ
H
=
57.32
k
J
.
.
.
.
.
(
1
)
H
2
(
g
)
+
1
2
O
2
(
g
)
⟶
H
2
O
(
l
)
Δ
H
=
−
286.20
k
J
.
.
.
.
.
(
2
)
Adding
e
q
n
(
1
)
&
(
2
)
, we have
H
2
O
(
l
)
+
H
2
(
g
)
+
1
2
O
2
(
g
)
⟶
H
+
(
a
q
.
)
+
O
H
−
(
a
q
.
)
+
H
2
O
(
l
)
;
Δ
H
=
(
57.32
)
+
(
−
286.20
)
k
J
H
2
(
g
)
+
1
2
O
2
(
g
)
⟶
H
+
(
a
q
.
)
+
O
H
−
(
a
q
.
)
;
Δ
H
=
−
228.88
k
J
Hence the value of enthalpy of formation of
O
H
−
ion at
25
℃
is
−
228.88
k
J
.
Suggest Corrections
1
Similar questions
Q.
Given, that,
H
2
O
(
l
)
→
H
+
(
a
q
)
+
O
H
−
(
a
q
)
;
Δ
H
=
57.32
k
J
H
2
(
g
)
+
1
2
O
2
(
g
)
→
H
2
O
(
l
)
;
Δ
H
=
−
286.02
k
J
Then, calculate the enthalpy of formation of
O
H
−
at
25
o
C
is:
Q.
On the basis of the following thermochemical data
H
2
O
(
g
)
⟶
H
+
(
a
q
)
+
O
H
−
(
a
q
)
;
Δ
H
=
57.32
k
J
H
2
(
g
)
+
1
2
O
2
(
g
)
⟶
H
2
O
(
l
)
;
Δ
H
=
−
286.2
k
J
The value of enthalpy of formation of
O
H
−
ion at
25
o
C
is:
Q.
Given that
;
H
2
O
(
l
)
→
H
+
(
a
q
)
+
O
H
−
(
a
q
)
;
Δ
H
=
57.32
kJ
H
2
(
g
)
+
1
2
O
2
(
g
)
→
H
2
O
(
l
)
;
Δ
H
=
−
286.02
kJ
Then calculate the enthalpy of formation of
O
H
−
at
25
o
C.
Q.
Consider the following reactions :
I)
H
+
(
a
q
)
+
O
H
−
(
a
q
)
=
H
2
O
(
l
)
;
Δ
H
=
−
X
1
k
J
.
m
o
l
−
1
II)
H
2
(
g
)
+
1
2
O
2
(
g
)
=
H
2
O
(
l
)
;
Δ
H
=
−
X
2
k
J
.
m
o
l
−
1
III)
C
O
2
(
g
)
+
H
2
(
g
)
=
C
O
(
g
)
+
H
2
O
(
l
)
;
Δ
H
=
+
X
3
k
J
.
m
o
l
−
1
IV)
C
2
H
2
(
g
)
+
5
2
O
2
(
g
)
=
2
C
O
(
g
)
+
H
2
O
(
l
)
;
Δ
H
=
+
X
4
k
J
.
m
o
l
−
1
Enthalpy of formation of
H
2
O
(
l
)
is:
Q.
Consider the following reactions:
(
i
)
H
+
(
a
q
)
+
O
H
–
(
a
q
)
→
H
2
O
(
l
)
,
Δ
H
=
–
X
1
kJ mol
–
1
(
i
i
)
H
2
(
g
)
+
1
2
O
2
(
a
q
)
→
H
2
O
(
l
)
,
Δ
H
=
–
X
2
kJ mol
–
1
(
i
i
i
)
C
O
2
(
g
)
+
H
2
(
g
)
→
C
O
(
g
)
+
H
2
O
(
l
)
,
Δ
H
=
–
X
3
kJ mol
–
1
(
i
v
)
C
2
H
2
(
g
)
+
5
2
O
2
(
g
)
→
2
C
O
2
(
g
)
+
H
2
O
(
l
)
,
Δ
H
=
X
4
kJ mol
–
1
Enthalpy of formation of
H
2
O
(
l
)
is:
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