Crude Oil & Fuels



Organic chemistry: Chemistry of carbon compounds, often obtained from living things

Element: 1 type of atom

Compound: 2 or more different elements chemically joined together

Mixture: 2 or more different elements which can be physically seperated

Oil: Made from bodies of sea creatures from millions of years ago

Crude Oil: Made of hydrocarbons ( These are made of ONLY hydrogen & carbon )

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Fractional Distillation

Crude oil is seperated by fractional distillation

Some substances in crude oil have different boiling points

Individual elements are not extracted, but groups with similar boiling points & properties, called fractions

Shorter molecules- ethane, propane etc. :

  • Less viscous ( Less gloopy)
  • More volatile ( Lower boiling point )
  • More flammable

The opposite is true for longer molecules

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Alkanes & Alkenes


  • These are saturated hydrocarbons
  • The general formula for an alkane is: C  H
  • Some examples:
    • Methane- 1 carbon
    • Ethane- 2 carbons
    • Propane- 3 carbons
    • Butane- 4 carbons etc.
  • Contain single, covalent bonds


  • These are unsaturated hydrocarbons
  • The general formula is: C  H
  • Some examples: Ethene, Propene, Butene etc
  • Contain one c=c double bond
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Combustion Of Hydrocarbons

Complete Combustion:

  • Rapid reaction between a substance & oxygen that releases heat & light energy
  • This occurs when there is plenty of oxygen- eg. bunsen burner
  • Characteristics:Blue flame, Very hot, Not sooty

Hydrocarbon + Oxygen   Carbon dioxide + Water

Eg.  Propane + Oxygen   Carbon dioxide + Water

      C  H       + 5O           3CO                + 4H O

Incomplete Combustion:

  • If there is a shortage of air, incomplete combustion takes place
  • This produces carbon monoxide and/ or carbon instead of carbon dioxide & water
  • It also releases less energy
  • Carbon monoxide is poisonous gas which reduces the ability of blood to carry oxygen
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Sulphur Dioxide // Global Dimming

When fossil fuels are burnt, sulphur impurities form sulphur dioxide, which causes acid rain

To prevent this, powdered calcium carbonate is mixed with water & reacted with sulphur dioxide

This makes neutral Calcium sulphate, which is used to make plaster

Calcium Sulphate + Sulphuric Acid    Calcium Sulphate + Carbon dioxide + Water


Global Dimming: Reduction in the amount of sunlight reaching the Earth's surface

  • Caused by particles from fossil fuels which collect water
  • Water droplets act like mirrors & relfect sunlight
  • Global dimming increases water droplets
  • The more water droplets, the less sunlight reaches the Earth
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Cleaner Fuels


  • Clean
  • Needs a different engine to use & energy from another source to create
  • Isn't widely available & Hard to store



  • Better for the environment & Cheaper
  • Carbon neutral & Biodegradeable
  • Requires large area to produce- destroys crop fields & habitats
  • Freezes faster than diesel- can ruin engine


  • Carbon neutral
  • Engines will nedd to be converted
  • Isn't widely available & Can raise food prices
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