GCSE AQA Chemistry 1 Fuels & The Environment

Crude Oil
1. Mixture of hydrocarbons
  1. Fuels made of carbon & hydrogen
  2. No chemical bonds - keep their original properties
    1. Can separate using fractional distillation
      1. Column works continuously - heated crude oil pumped in at bottom
        Vaporised oil rises up & various fractions tapped off as they condense
2. Properties
  1. Made up of hydrocarbons - alkanes
    1. Chains of carbon atoms surrounded by hydrogen atoms
      1. Different length chains
      2. Carbon forms 4 bonds & hydrogen forms 1
    2. First 4: Methane, Ethane, Propane, Butane
      1. Forms as many bonds as possible - saturated
    3. Shorter molecules - more runny (less viscous)
      1. Shorter molecules - more volatile
        Shorter molecules - more flammable
  2. General formula: CnH2n+2
3. Uses
  1. Volatilty - refinery gas - good as bottled gas
    1. Petrol - higher boiling point - liquid
      1. Viscous hydrocarbons - lubricants
Crude oil as a fuel
1. Burn cleanly so good fuels
  1. Transport, central heating, power stations
2. Also provides raw materials for making chemicals - plastics
3. Alternatives are possible but things are set up for oil fractions - easier, cheaper & more reliable
4. Will run out - non-renewable fuel
  1. New reserves being discovered & technology improving
  2. Should start conserving & finding alternatives
Environmental problems
1. Burning fossil fuels
  1. Power stations & cars
  2. hydrocarbon + oxygen --> carbon dioxide + water vapour
    1. Energy (heat) also produced
    2. If fuel contains sulphur impurities - sulphur dioxide released
      1. If enough oxygen - complete combustion, if not then partial
        Soot, unburnt fuel & carbon monoxide released
        Global Dimming - particles reflect sunlight back into Space
      2. Causes acid rain - sulphur dioxide mixes with clouds to form dilute sulphuric acid
        Same with nitrogen oxides
        Plants & animals die, kills trees, damages limestone buildings & statues & possible health probs
        Reducing sulphur emissions
        Can be removed before burning - £££
        Power stations have Acid Gas Scrubbers - take harmful gas out before release
2. Increasing carbon dioxide = Climate Change
  1. Causes global warming, changing rainfall patterns, flooding
3. Alternative fuels being developed
  1. Ethanol - plant material - biofuel from fermentation
    1. Carbon neutral, engines need to be converted, stop growing crops
  2. Biodiesel - vegetable oils
    1. Carbon neutral, don't need to convert engines, can't make enough to replace diesel, expensive
  3. Hydrogen gas - electrolysis of water
    1. Clean, need special engine, not widely available, hard to store

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GCSE AQA Chemistry 1 Fuels & The Environment

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