Standard Heats of combustion of Graphite, Hydrogen and Ethene are -95K.Cal, -65K.Cal and -220K.Cal respectively. Calculate Heat of combustion of Ethene
Answers
Answer:
We have to calculate the heat of formation of ethane.
The reaction of formation of ethane is,
2C
(s)
+3H
2(g)
→C
2
H
6(g)
Heat of combustion of ethane is, −1560 kJ/mol
C
2
H
6(g)
+
2
7
O
2
(g)→2CO
2
+3H
2
O ----- (I)
ΔH=−1560 kJ/mol
Heat of combustion or hydrogen is, −393.5 kJ/mol
H
2(g)
+
2
1
O
2(g)
→H
2
O
(g)
------- (II)
ΔH=−393.5 kJ/mol
Heat of combustion of graphite is, −286 kJ/mol
C(s)+O
2
(g)→CO
2(g)
___(III)
ΔH=−286 kJ/mol
Multiply equation (III) by 2 multiply equation (II) by 3 and inverse equation (I)
22C
(s)
+2O
2(g)
→2CO
2(g)
-------- 1
ΔH
1
=−286×2=−572 kJ/mol
3H
2
+
2
3
O
2
(g)→3H
2
O(g) ------ 2
ΔH
2
=−393.5×3=−1180.5 kJ/mol
2CO
2(g)
+3H
2
O
(g)
→C
2
H
6
(g)+
2
7
O
2
(g) ----3
ΔH
3
=1560 kJ/mol
Adding 1, 2 and 3 equation, we get
2C
(s)
+3H
2
(g)→C
2
H
6
(g)
ΔH=ΔH
1
+ΔH
2
+ΔH
3
=−572−1180.5+1560
ΔH=−192.5 kJ/mol
Answered By
toppr
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