Crude oil and fuels Cambridge IGCSE Co-ordinated Sciences (9–1) revision
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In plain words
Crude oil (petroleum) is a thick black mixture of hundreds of different hydrocarbons, useless as it comes out of the ground. An oil refinery sorts it by boiling point into batches called fractions: petrol, diesel, jet fuel and so on, each with its own job.
Three things to know
- A hydrocarbon contains hydrogen and carbon only. Coal, natural gas (mainly methane) and petroleum are fossil fuels.
- Fractional distillation: the oil is heated until it is a vapour, and rises up a tall column that is cooler at the top. Each fraction condenses at its own height. Small molecules with low boiling points come off at the top.
- From the top: refinery gas (bottled gas), gasoline (petrol for cars), kerosene (jet fuel), diesel, fuel oil (ships, heating), bitumen (roads). Longer molecules are thicker, harder to light and have higher boiling points.
Tips and tricks
- Top of the column: small molecules, low boiling point, runny, catch fire easily. Bottom: the opposite of all four.
- A hydrocarbon contains hydrogen and carbon only. Leave out "only" and you lose the mark.
It lands in your notebook with its questions as flashcards.
Crude oil and fuels: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What do hydrocarbons contain?
The name says it: hydro(gen) and carbon.
What is the main compound in natural gas?
Natural gas is mostly CH₄.
Which fraction is used as fuel for aircraft?
Kerosene is jet fuel.
Which fraction has the lowest boiling point?
It has the smallest molecules and comes off at the top of the column.
What is bitumen used for?
It is the thick, sticky fraction left at the bottom.
How does viscosity change as hydrocarbon chains get longer?
Longer molecules flow less easily.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
4 questions, 9 marks. Write your answers on paper, then check them.
Crude oil and fuels
Cambridge IGCSE Co-ordinated Sciences (9–1) 0973 · 9 marks · papermunch.org
Name ______________________________ Date ______________
State what is meant by a hydrocarbon, and name the main hydrocarbon in natural gas.[2]
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A compound containing hydrogen and carbon only. Methane.
Describe how fractional distillation separates crude oil into fractions.[3]
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The oil is heated until it vaporises. The vapour rises up a column that is hot at the bottom and cooler at the top. Each fraction condenses where the temperature falls just below its boiling point, and is run off.
Give one use of kerosene and one use of bitumen.[2]
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Kerosene: fuel for aircraft (jet fuel). Bitumen: making roads (or roofing).
Describe how the properties of the hydrocarbons change as the molecules get longer.[2]
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Any two: the boiling point rises; they become more viscous (thicker); they become harder to ignite (less flammable).
Answers: Crude oil and fuels
- 1. A compound containing hydrogen and carbon only. Methane.
- 2. The oil is heated until it vaporises. The vapour rises up a column that is hot at the bottom and cooler at the top. Each fraction condenses where the temperature falls just below its boiling point, and is run off.
- 3. Kerosene: fuel for aircraft (jet fuel). Bitumen: making roads (or roofing).
- 4. Any two: the boiling point rises; they become more viscous (thicker); they become harder to ignite (less flammable).