SC20

• Crude means impure so crude oil has a mixture of different substances.

  The different parts are called fractions which have a mix of different molecules called hydrocarbons.
• Hydrocarbons have similar boiling points because of their covalent bonding
• Fractionating columns are towers that collect different fractions of crude oil depending on their boiling point.

  The heat source is at the bottom so fractions are distillated from lowest boiling point at the top to highest boiling point at the bottom
• Boiling Point - the temperature at which a substance boils

  Flammability - how easily a substance catches fire

  Viscosity - how thick and runny a substance is

  Energy Content - the amount of heat energy released by a fuel

  Volatility - how easily a substance changes from a liquid/solid to a gas
• Crude Oil Fractionating Column:

  1. Gases - domestic heating and cooking
  2. Petrol - fuel for cars
  3. Kerosene - fuel for aircrafts
  4. Diesel Oil - fuel for some cars and trains
  5. Fuel Oil - fuel for large ships and some power stations
  6. Bitumen - surfacing roads and roofs

  Phrase to Help Remember: Good People Kill Dumb Fucking Bitches
• As you go down the Crude Oil Fractionating Column:

  • number of carbon atoms increases
  • volatility decreases
  • boiling point increases
  • flammability decreases
  • viscosity increases
• Hydrocarbon - a molecule that contains only carbon and hydrogen which are joined by covalent bonds

  Most hydrocarbons in crude oil are compounds called alkanes
• Alkanes are a family of hydrocarbon compounds with the general formula CnH2n+2
• Homologous Series - family or organic molecules that have the same general formula, similar chemical properties because of the same functional group, physical properties and show a gradual trend meaning each member has a one unit difference
• Alkanes contain only single carbon-carbon (C-C) bonds so are saturated
• There are two types of combustion:

  • Complete Combustion - plentiful supply of oxygen (excess)
  • Incomplete Combustion - limited supply of oxygen (carbon monoxide is toxic + soot)
• Carbon monoxide is poisonous because it binds to haemoglobin which prevents us from breathing oxygen.

  This causes unconsciousness and leads to death via suffocation.
• Test for Carbon Dioxide - limewater turns cloudy

  Test for Water - blue cobalt chloride paper turns pink
• Sulphur Dioxide:

  • most crude oil and coal deposits contain sulphur as an impurity
  • when fuel burns, sulphur is also burned to produce sulphur dioxide
  • the gas dissolves in rainwater, forming a very acidic solution known as acid rain (sulphuric/sulphurous acid)

  S + O2 ---> SO2
• Oxides of Nitrogen:

  • high temperatures/spark in combustion engines causes nitrogen to react with oxygen to produce nitric oxide or nitrogen dioxide
  • NO2 causes photochemical smog and dissolves in rainwater which forms an acidic solution contributing to acid rain
• Ways of Reducing Pollution:

  • most modern car exhausts are now fitted with catalytic converters which turn dangerous products into less harmful gases
• Hydrogen as a Fuel:

  • only combustion product is water which has no environmental impact (advantage)
  • more energy released per fuel gram than petrol (advantage)
  • not many filling stations that sell hydrogen (disadvantage)
  • made by the electrolysis of water so is renewable (advantage)
  • highly flammable so difficult to store (disadvantage)
  • most would have to be modified (disadvantage)
• There is only a finite supply of crude oil derived fuels so they are non-renewable
• Cracking - breaking up or splitting a long chain alkane into two shorter chains
• Long chain alkane is cracked into a more useful short chain alkane and an alkane used to make polymers using high temperatures with a catalyst

  • catalyst speeds up reaction (silicon dioxide/aluminium oxide)
  • decreases operating temperature
  • needs high temperatures to break covalent bonds (600-700'C)