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Chemistry
The standard molar heat of formation of ethane, CO2 and water are respectively -21.1, -94.1 and -68.3 kcal. The standard molar heat of combustion of ethane will be
Q. The standard molar heat of formation of ethane,
C
O
2
and water are respectively
−
21.1
,
−
94.1
and
−
68.3
k
c
a
l
. The standard molar heat of combustion of ethane will be
2981
204
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A
-372 kcal
53%
B
162 kcal
22%
C
-240 kcal
19%
D
183.5 kcal
6%
Solution:
Given,
(i)
2
C
+
3
H
2
⟶
C
2
H
6
;
Δ
H
=
−
21.1
(ii)
C
+
O
2
⟶
C
O
2
;
Δ
H
=
−
94.1
(iii)
H
2
+
2
1
O
2
⟶
H
2
O
;
Δ
H
=
−
68.3
Eqs. 2 (ii)
+
3
(iii) - (i)
C
2
H
6
+
2
3
O
2
⟶
2
C
O
2
+
3
H
2
O
Δ
x
=
2
(
−
94.1
)
+
3
(
−
68.3
)
−
(
−
21.1
)
=
−
372
k
c
a
l