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Question
Chemistry
The enthalpy of formation (Δ Hf) of methanol, formaldehyde and water are -239,-116 and -286 kJ mol -1 respectively. The enthalpy change for the oxidation of methanol to formaldehyde and water in kJ is
Q. The enthalpy of formation
(
Δ
H
f
)
of methanol, formaldehyde and water are
−
239
,
−
116
and
−
286
k
J
m
o
l
−
1
respectively. The enthalpy change for the oxidation of methanol to formaldehyde and water in
k
J
is
1369
208
AP EAMCET
AP EAMCET 2017
Report Error
A
-136
B
-173
C
163
D
-163
Solution:
Given
H
f
∘
, for
C
H
3
O
H
=
−
239
k
J
m
o
l
−
1
H
.
C
H
O
=
−
116
k
J
m
o
l
−
1
H
2
O
=
−
286
k
J
m
o
l
−
1
0
Required relation:
2
C
H
3
O
H
+
O
2
⟶
2
H
C
H
O
+
2
H
2
O
Δ
H
R
=
2
1
H
f
∘
of H.CHO. and
H
2
O
Δ
H
R
=
2
1
H
f
∘
[(
2
x
−
116
)
+
(
2
x
−
286
)]
−
1
[(
2
×
239
)]
=
2
1
[(
−
232
)
+
(
−
572
)]
−
[
−
478
]
=
2
1
[
−
804
+
478
]
⇒
2
1
[
−
326
]
=
−
163
k
J
m
o
l
−
1