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Most of the fuels used today are obtained from crude oil - Edexcel - GCSE Chemistry Combined Science - Question 1 - 2019 - Paper 1
Question 1
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Most of the fuels used today are obtained from crude oil.
(a) Which statement about crude oil is correct?
1 A crude oil is a compound of different hydrocar... show full transcript
Worked Solution & Example Answer:1
Most of the fuels used today are obtained from crude oil - Edexcel - GCSE Chemistry Combined Science - Question 1 - 2019 - Paper 1
Step 1
Which statement about crude oil is correct?
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Answer
The correct statement is that crude oil is a mixture of hydrocarbons (Option B). Crude oil is not a single compound but a complex mixture of various hydrocarbons that can vary in composition.
Step 2
State a use for each of these fractions.
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Answer
Kerosene is commonly used as a fuel for jet engines in aviation, while diesel oil is primarily used in diesel engines for vehicles.
Step 3
Choose a property.
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Answer
A property to compare is the boiling point. Kerosene has a lower boiling point than diesel oil, which is why it is collected higher in the fractionating column.
Step 4
Explain, using these formulae, why butane and pentane are neighbouring members of the same homologous series.
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Answer
Butane (C₄H₁₀) and pentane (C₅H₁₂) are neighbouring members of the homologous series of alkanes. They differ by the addition of one methylene (-CH₂-) group, which gives them similar chemical properties while maintaining a distinct formula. Each subsequent member of this series increases by the same amount, providing a systematic relationship in their structural formulas.
Step 5
Calculate the mass of carbon in 100g of butane.
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Answer
To calculate the mass of carbon in 100g of butane (C₄H₁₀), first determine its molar mass:
Molar mass of butane = 4 × 12.0 (for C) + 10 × 1.00 (for H) = 58.0 g/mol
Now, calculate the mass of carbon:
Mass of carbon in 1 mole of butane = 4 × 12.0 = 48.0 g
In 100g of butane, the mass of carbon is:
rac{48.0 ext{ g}}{58.0 ext{ g/mol}} imes 100 ext{ g} \\ = 82.76 ext{ g}
Rounding to three significant figures gives the mass of carbon as 82.8 g.
