Crude oil

• Crude oil


  Thick black liquid made of a large number of different compounds mixed together, mostly hydrocarbons of various sizes
• Crude oil is formed from the remains of ancient biomass-living organisms (mostly plankton) that died many millions of years ago
• Hydrocarbons


  • compounds made of carbon and hydrogen only
• Combustion


  Reaction of hydrocarbons with oxygen that releases a lot of energy
• Complete combustion


  Combustion where the only products are carbon dioxide and water
• Properties that determine if a hydrocarbon is useful as a fuel


  • Flammability
  • Boiling point
  • Viscosity
• First four alkanes


  • Methane
  • Ethane
  • Propane
  • Butane
• Fractional distillation


  Process to separate the different hydrocarbons in crude oil based on their boiling points
• Fractional distillation process


  1. Crude oil is vaporised

  2. Hydrocarbon gases enter the column

  3. Gases rise up the column and cool down

  4. Hydrocarbons condense at their boiling point

  5. Hydrocarbon fraction is collected
• Products from fractional distillation

  • Petrol
  • Diesel
  • Kerosene
  • Heavy oils
  • Liquefied petroleum gases
• Cracking


  Process to break up longer hydrocarbons into shorter ones
• Cracking methods


  • Catalytic cracking
  • Steam cracking
• Alkenes


  Family of hydrocarbons that contain double bonds between carbon atoms
• Alkenes are more reactive than alkanes, they turn bromine water from orange to colourless
• Glossary terms


  • Alkane
  • Alkene
  • Cracking
  • Distillation
  • Double bond
  • Flammable
  • Fraction
  • Fractional distillation
  • General formula
  • Hydrocarbon
  • Mixture
  • Saturated hydrocarbon
  • Thermal decomposition
  • Unsaturated hydrocarbon
  • Viscosity
• Fractions from crude oil

  • Very flammable, colourless, very runny (20-60°C)
  • Less flammable, pale yellow, runny (60-100°C)
  • Quite flammable, yellow, viscous (100-140°C)
  • Not very flammable, orange, very viscous (140-180°C)
• Burning alkanes experiment


  1. Identify products formed when hydrocarbons burn in air

  2. Complete combustion produces carbon dioxide and water

  3. Incomplete combustion produces carbon monoxide and water
• Carbon monoxide is dangerous because it is toxic, colourless and odourless, and binds irreversibly to haemoglobin reducing the blood's capacity to transport oxygen
• Evaporate


  Process of turning something from liquid to vapour
• Hydrocarbon


  Compounds made of only hydrogen and carbon
• Condense


  Vapour cooling to a liquid state
• Fraction


  Hydrocarbons with similar boiling points separated from crude oil
• Fractional distillation process


  1. Crude oil is heated and evaporates

  2. Vapours move up the fractionating column

  3. As gases cool, they condense at their boiling point

  4. Each fraction is collected at a different point
• Bitumen has a very high melting point and does not evaporate when the crude oil mixture is heated
• Refinery gases have very low boiling points and do not condense, passing out of the top of the fractionating column
• Each fraction contains hydrocarbons with a similar number of carbon atoms