the enthalpy of the formation of CO2 & H2O are -395KJ &-285KJ respectively and the enthalpy of combustion of acetic acidis 869KJ. The enthalpy of acetic acid is?
Answers
Answered by
1
Answer:
491.8kJ/mol
Explanation:
Combustion reaction for above question is
C
2
H
4
O
2
+
2
O
2
→
2
C
O
2
+
2
H
2
O
Δ
H
f
(
c
o
m
b
u
s
t
i
o
n
)
=
2
[
Δ
H
C
O
2
+
Δ
H
H
2
O
]
−
Δ
H
C
2
H
4
O
2
Δ
H
C
2
H
4
O
2
=
2
[
Δ
H
C
O
2
+
Δ
H
H
2
O
]
−
Δ
H
c
o
m
b
u
s
t
i
o
n
Δ
H
C
2
H
4
O
2
=
867
+
(
2
×
−
679.4
)
=
−
491.8
k
J
m
o
l
Answered by
1
ΔH(combustion) = -860kJ/mol
ΔH(CO2) = -393.5kJ/mol
ΔH(H20) = -285.9kJ/mol
# Solution-
Combustion reaction occurs as follows,
C2H4O2 + 2O2 --> 2CO2 + 2H2O
Enthalpy of combustion is given by,
ΔH(combustion) = 2ΔH(CO2) + 2ΔH(H2O) -ΔH(C2H4O2)
ΔH(C2H4O2) = 2ΔH(CO2) + 2ΔH(H2O) - ΔH(combustion)
ΔH(C2H4O2) = 2×(-393.5) + 2×(-285.9) - (-860)
ΔH(C2H4O2) = -498.8 kJ/mol
# Enthalpy of formation of acetic acid is -498.8 kJ/mol.
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