Where hydrocarbons come from, fractional distillation of petroleum and the uses of its fractions, and thermal and catalytic cracking of large alkanes into smaller, more useful molecules.
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Trinidad and Tobago and Guyana are Caribbean oil and gas producers. The same fractional distillation that makes petrol also gives us the raw materials for plastics.
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Compound of carbon and hydrogen only.
Natural gas (mainly methane) and petroleum (crude oil).
Crude oil separated by boiling point: small molecules at the top.
Gas: cooking; petrol: fuel; naphtha: plastics; kerosene: jets; diesel; fuel oil; bitumen: roads.
Long alkane → shorter alkane + alkene.
~800 °C, high pressure vs ~500 °C with zeolite.
More demand for petrol and alkenes.
CO₂, CO, SO₂, oil spills; fossil fuels are finite.
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8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
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Question 1 [15 marks]
Crude oil is a mixture of hydrocarbons that is separated by fractional distillation in a refinery.
(a) (a) State two natural sources of hydrocarbons. [2]
(b) (b) Define the term hydrocarbon. [1]
(c) (c) Explain how fractional distillation separates crude oil. [4]
(d) (d) State one use for each of three fractions. [3]
(e) (e) Describe cracking and write an equation for the cracking of decane, C₁₀H₂₂, into octane and one other product. [4]
(f) (f) Give one reason why cracking is carried out. [1]
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