AQA GCSE Chemistry Trilogy: Hydrocarbons and Alkanes

Crude Oil:

• Hydrocarbons are compounds that contain hydrogen and carbon atoms only.
• Crude oil is a finite resource that is found in the Earth’s crust.
• It is the remains of organisms that lived and died millions of years ago - mainly plankton, which was buried in mud.
• Crude oil is a complex mixture of hydrocarbons.
• Used as -
  • Fuels such as petrol, diesel, kerosene, heavy fuel oil and liquefied petroleum gases
  • Feedstock for the petrochemical industry
  • Solvents
  • Lubricants
  • Detergents
• A feedstock is a raw material used to provide reactants for an industrial reaction.
• A petrochemical is a substance made from crude oil using chemical reactions.

Alkanes:

• Form a homologous series - A 'family' of organic compounds that have the same functional group and similar chemical properties. Alkanes:

  • have the same general formula
  • differ by CH2 in molecular formulae from neighbouring compounds
  • show a gradual variation in physical properties, such as their boiling points
  • have similar chemical properties

• The general formula for the alkanes is CnH(2n+2), where n is the number of carbon atoms in the molecule.

• Alkanes are saturated hydrocarbons:

  • Hydrocarbons, because they are compounds containing hydrogen and carbon only
  • Saturated, because their carbon atoms are joined by C-C single bonds