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Crude oil is a mixture of hydrocarbons - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2016 - Paper 1
Question 3
Crude oil is a mixture of hydrocarbons. It can be separated into fractions. (a) Which of these mixtures shows formulae of substances that could be in the gaseous fr... show full transcript
Worked Solution & Example Answer:Crude oil is a mixture of hydrocarbons - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2016 - Paper 1
Step 1
Which of these mixtures shows formulae of substances that could be in the gaseous fraction of crude oil?
Answer
The gaseous fraction of crude oil mainly consists of light hydrocarbons, which are typically alkanes. Among the options:
- A: CₙH₂ₙ, CₙH₂ₙ, Br, CₙHₙO - includes bromine and oxygen, not ideal for gaseous
- B: CₙH₂ₙ, CₙHₙBr, CₙHₙO - same issue as A
- C: CₙHₙ, CₙH₂ₙ, CₙHₙO - suitable hydrocarbons but includes oxygen
- D: CₙH₂ₙ, Br, CₙHₙO - unsuitable due to Br and O
Thus, C is the best option, as it encompasses hydrocarbons without Br or O, suggesting they could exist in a gaseous state.
Step 2
State which oil well contains the greatest combined total of diesel oil and fuel oil.
Answer
To find the total of diesel oil and fuel oil for each well:
- Oil Well A: Diesel oil (7) + Fuel oil (26) = 33
- Oil Well B: Diesel oil (10) + Fuel oil (28) = 38
- Oil Well C: Diesel oil (16) + Fuel oil (30) = 46
The highest total is from Oil Well C.
Step 3
State which oil well produces a crude oil containing the highest percentage of the high boiling point fractions.
Answer
High boiling point fractions refer to diesel oil, fuel oil, and bitumen traditionally. We analyze:
- Oil Well A: Total of high boiling point = 7 (diesel) + 26 (fuel) + 58 (bitumen) = 91% of crude oil
- Oil Well B: Total = 10 + 28 + 27 = 65%
- Oil Well C: Total = 16 + 30 + 1 = 47%
Thus, Oil Well A has the highest percentage of the high boiling point fractions.