A 2 L sample of a gaseous hydrocarbon is burnt in excess oxygen - VCE - SSCE Chemistry - Question 7 - 2004 - Paper 1
Question 7
A 2 L sample of a gaseous hydrocarbon is burnt in excess oxygen. The only products of the reaction are 8 L of CO₂(g) and 10 L of H₂O(g), all at 100°C and 1 atm press... show full transcript
Worked Solution & Example Answer:A 2 L sample of a gaseous hydrocarbon is burnt in excess oxygen - VCE - SSCE Chemistry - Question 7 - 2004 - Paper 1
Step 1
Identify the reaction
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Answer
We start with a gaseous hydrocarbon (CₓHᵧ), which combusts in excess oxygen to produce carbon dioxide (CO₂) and water (H₂O). The balanced equation generally looks like:
ightarrow x ext{CO}_2 + rac{y}{2} ext{H}_2 ext{O}$$
Step 2
Applying the volumes given
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Answer
According to the question, we have:
8 L of CO₂ produced
10 L of H₂O produced
Using the stoichiometric relationships from the balanced equation, we can identify the coefficients:
x = 8 (for CO₂), and
y/2 = 10, therefore y = 20.
This gives us the ratio:
C: x = 8
H: y = 20.
Step 3
Finding the simplest molecular formula
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Answer
Now we find the simplest whole-number ratio of C to H:
x:y=8:20=2:5
Thus, we deduce the molecular formula is C₂H₅.
Step 4
Select the correct answer
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Answer
From the available options, we identify C₂H₁₀, which corresponds to the molecular formula of C₂H₅ expanded with additional hydrogen. Therefore, the answer is option C: C₂H₁₀.
