0.25 moles of a hydrocarbon, on combustion gives 1.0mole each of CO2 and steam. The hydrocarbon is
Answers
Answer:
Explanation:
C
3
H
8
Explanation:
The trick here is to recognize the fact that you're dealing with a hydrocarbon, which means that it will only contain carbon and hydrogen.
Now, the complete combustion of a hydrocarbon produces carbon dioxide,
CO
2
, and water,
H
2
O
.
In your case, you know that when
0.1
moles of this hydrocarbon underwent combustion, the reaction produced
0.3
moles of carbon dioxide and
0.4
moles of water.
Now, another important thing to realize here is that all of the carbon that was initially a part of the hydrocarbon is now a part of the carbon dioxide, and all of the hydrogen that was a part of the hydrocarbon is now a part of the water.
Since one mole of carbon dioxide contains
1
mole of carbon, and one mole of water contains
2
moles of hydrogen, it follows that the hydrocarbon contained
0.3
moles CO
2
⋅
1 mole C
1
mole CO
2
=
0.3 moles C
and
0.4
moles H
2
O
⋅
2 moles H
1
mole H
2
O
=
0.8 moles H
Now, let's say that your hydrocarbon has a molecular formula
C
x
H
y
. You know that one mole of this hydrocarbon would produce
x
a
moles of C
y
a
moles of H
If this is the case, you can say that
0.1
moles of this hydrocarbon will produce
(
0.1
×
x
)
a
moles of C
(
0.1
×
y
)
a
moles of H
But you already know how many moles of carbon and hydrogen were produced by the reaction, so you can say that
0.1
×
x
=
0.3
⇒
x
=
0.3
0.1
=
3
and
0.1
×
y
=
0.8
⇒
y
=
0.8
0.1
=
8
Therefore, the molecular formula of the hydrocarbon is
C
3
H
8
→
propane