Specification Point 4.11:
Know that a fuel is a substance that, when burned, releases heat energy


Fuel: Substance which when burned, releases heat energy

  • This heat can be transferred into electricity, which we use in our daily lives


Fuel examples, Edexcel IGCSE Chemistry

Oil, coal and natural gases, which are common fossil fuels used to provide us with electricity

Specification Point 4.12:
Know the possible products of complete and incomplete combustion of Hydrocarbons with Oxygen and air

Products of Combustion

Complete combustion: Occurs when there is an unlimited supply of air so that elements in the fuel react fully with oxygen.

Complete combustion of hydrocarbons:

During the complete combustion of hydrocarbons, carbon dioxide and water will be produced:

  • Carbon will oxidise to form carbon dioxide
  • Hydrogen will oxidise to water


Hydrocarbon   +   Oxygen   →   Carbon dioxide   +   Water

Incomplete combustion: Occurs when there is a limited supply of air so that elements in the fuel do not fully react with Oxygen

Incomplete combustion of Hydrocarbons:

During the incomplete combustion of hydrocarbons, water will still be produced but instead of carbon dioxide, carbon monoxide (soot) will form


Hydrocarbon   +   Oxygen   →   Carbon Monoxide   +   Water

Specification Point 4.13:
Understand why Carbon monoxide is poisonous, in terms of its effect on the capacity of blood to transport Oxygen

Carbon Monoxide

Carbon monoxide: A poisonous gas that is colourless and odourless, produced during incomplete combustion:

Hydrocarbon   +   Oxygen   →   Carbon monoxide   +   Water

Effect of Carbon monoxide on blood:

  • When carbon monoxide is produced by incomplete combustion, it is absorbed in the lungs and binds with the haemoglobin in our red blood cells.
  • This reduces the capacity of the blood to carry oxygen.
Carbon monoxide atoms, Edexcel IGCSE Chemistry

Carbon monoxide atoms

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.