Fuels and Earth Science

• What is a fuel?

  A fuel is a substance that can be used to release useful amounts of energy when they burn e.g. wood, oil, gas, coal
• Hydrocarbon


  A compound made up of hydrogen and carbon only e.g. Methane (CH4)
• The compounds produced by the distillation of crude oil are all hydrocarbons
• Formation of crude oil

  -Microscopic plants and animals die and fall to the sea bed

  -Layers of sand and mus form on top

  -Pressure and high temperature causes oil to form

  -Oil is then obtained by drilling
• Crude oil


  -Crude oil is a complex mixture of hydrocarbons

  -It contains Carbon atoms joined together in chains or rings

  -The structure of these rings or chains determines the hydrocarbons' properties
• Distillation of water and ethanol

  (Simple distillation)

  
• More on distillation 


  The boiling points of water (100 degrees) and ethanol (78 degrees) is what makes them separate efficiently
• Fractional distillation of crude oil

  The crude oil is evaporated and the hydrocarbon chains of different lengths condense at different temperatures

  
• More on fractional distillation

  -The longer the molecule, the greater the greater the intermolecular forces therefore, the higher the boiling points and the further down the column they collect

  -Small molecules collect towards the top because of their low boiling points (gases)

  -The hottest part of the fractionating column is at the bottom and chain lengths and viscosity increase
• Homologous series


  -They are compounds with the same general formula and same chemical properties

  -They have similar trends in physical properties
• Alkanes


  A homologous series with a functional group of a single C-C bond or in the first case a single C-H bond. They are said to be saturated because they already have the maximum amount of hydrogen bonds
• More on alkanes


  If you break a single bond of this homologous series, the molecule will be ruined
• Alkenes


  A functional group of a double C-C bond. This homologous series is unsaturated
• How to distinguish between alkanes and alkenes 


  Alkenes stay colourless upon bromine water being added but alkanes go orange
• Alkene + Bromine


  ethene + bromine ---> 1,2 - dibromoethane