Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want fuels — fossil fuels, fractional distillation of petroleum and environmental impacts — to become reliable marks instead of vague lists of “things from crude oil”.
What query it owns: how to understand and revise fuels in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the fuels revision-guide angle, while Tutopiya’s Fuels subtopic page owns the learning resource and the free Fuels quiz owns the practice.

Fuels store energy that is released during combustion. Cambridge IGCSE Coordinated Science (0654) tests fossil fuels (coal, oil, natural gas), fractional distillation of crude oil, the uses of each fraction, and the environmental problems caused by burning fuels. This guide covers the syllabus definitions, fraction tables examiners expect, and the question types that appear every year.

Key takeaways

• Fossil fuels (coal, crude oil, natural gas) formed from ancient organic matter over millions of years.
• Fractional distillation separates crude oil into fractions by boiling point in a fractionating column.
• Hydrocarbons in each fraction have similar chain lengths and properties.
• Complete combustion of hydrocarbons produces CO₂ and H₂O; incomplete combustion produces CO and soot.
• Burning fossil fuels releases CO₂, SO₂ and other pollutants, contributing to climate change and acid rain.

What are fuels in Cambridge IGCSE Coordinated Science?

A fuel is a substance that releases useful energy when burned. At IGCSE level, the focus is on hydrocarbon fuels from crude oil — separated by fractional distillation into fractions such as refinery gases, petrol, kerosene, diesel and bitumen. Each fraction has different boiling points, volatility and uses. Examiners also test the environmental consequences of fuel combustion and alternatives such as biofuels and renewable energy.

Read the full notes on Tutopiya’s Fuels subtopic page before attempting questions.

The core ideas you must master

Idea	What it means	How the exam uses it
Fossil fuels	Non-renewable energy sources	”State why fossil fuels are non-renewable.”
Fractional distillation	Separate by boiling point	”Describe how petrol is obtained from crude oil.”
Fraction uses	Match fraction to application	”Give a use of kerosene.”
Complete combustion	Plenty of oxygen → CO₂ + H₂O	”Write products of complete combustion.”
Pollution	CO₂, CO, SO₂, particulates	”Describe an environmental problem from fuels.”

Crude oil fractions — boiling point and uses

Fraction	Chain length (approx.)	Boiling point	Use
Refinery gas	C₁–C₄	Lowest	LPG, camping gas
Gasoline (petrol)	C₅–C₁₀	Low	Car fuel
Kerosene (paraffin)	C₁₀–C₁₆	Medium	Jet fuel, heating
Diesel oil	C₁₄–C₂₀	Higher	Lorries, trains
Fuel oil	Long chains	High	Ships, power stations
Bitumen	Very long chains	Highest (residue)	Road surfacing, roofing

Fractional distillation of crude oil — step by step

1. Crude oil is heated in a furnace until most of it vaporises.
2. Vapour enters a fractionating column that is hot at the bottom, cool at the top.
3. Fractions with lower boiling points rise higher and condense at cooler levels.
4. Fractions with higher boiling points condense near the bottom.
5. Each fraction is collected at a different tray level.

Complete vs incomplete combustion

Type	Conditions	Products	Problem
Complete	Plenty of oxygen	CO₂ + H₂O	CO₂ contributes to greenhouse effect
Incomplete	Limited oxygen	CO + C (soot) + H₂O	CO is toxic; soot causes respiratory disease

Fuels in past-paper wording

Command word	What the question wants	Typical stem
Describe	Fractional distillation process	”Describe how crude oil is separated.”
State / Give	Use of a fraction	”Give a use of bitumen.”
Explain	Why fractions differ	”Explain why petrol boils before diesel.”
Write equation	Combustion products	”Write products of methane combustion.”
Suggest	Environmental issue or alternative	”Suggest a problem with burning coal.”

Worked exam-style stems

1. “Describe how petrol is obtained from crude oil.” Crude oil heated and vaporised → vapour enters fractionating column → fractions condense at different heights according to boiling point → petrol (low b.p.) collected near the top. Reward: heating + fractionating column + boiling point separation.
2. “Give one use of kerosene and one use of bitumen.” Kerosene: jet fuel / heating; bitumen: road surfacing / roofing. Reward: one valid use for each.
3. “Explain why burning fossil fuels contributes to global warming.” Fossil fuels contain carbon; combustion produces CO₂, a greenhouse gas that traps infrared radiation and raises global temperatures. Reward: CO₂ produced + greenhouse effect.

Practise on the Fuels quiz.

How fuels connect to the syllabus

Fuels link to Alkanes (hydrocarbon combustion), Carbon Dioxide and Methane (greenhouse gases) and Sulfur (SO₂ from impure fuels). The Cambridge IGCSE Coordinated Science resource hub links every Organic Chemistry subtopic.

Common mistakes students make

• Confusing fractional distillation of crude oil with fractional distillation of liquid air.
• Saying fractions are separated by density (separated by boiling point).
• Forgetting incomplete combustion produces carbon monoxide, not CO₂.
• Placing bitumen at the top of the column (it is the bottom residue).
• Listing fractions without linking to uses when the question asks for both.

When you need more support

If fuels and fractional distillation questions keep costing marks, work through the Fuels quiz, then get help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

Why are fossil fuels called non-renewable? They take millions of years to form and are being used much faster than they can be replaced.

How is crude oil separated into fractions? By fractional distillation — heating the oil and collecting fractions that condense at different heights in a fractionating column according to boiling point.

What are the products of complete combustion of a hydrocarbon? Carbon dioxide and water.

How do I revise fuels effectively? Learn the fraction table, distillation steps, combustion products and environmental effects, then take the quiz.

Ready to master Cambridge IGCSE Coordinated Science fuels?

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