Chemistry AS DF 6 - 10

  • Created by: A.B.
  • Created on: 01-12-13 17:25
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  • DF Pollution from Cars SL DF 6 - DF 10
    • Production and Effects of Pollutants from Petrol
      • Unburnt Hydrocarbons
        • Evaporative emissions and incomplete combustion
          • Contributes to formation of photochemical smog, causing respiratory problems
      • Carbon Monoxide
        • Incomplete combustion of hydrocarbons
          • Toxic to us, it decreases the uptake of oxygen by the blood
            • Reduced by catalytic converters and oxygenates but this means carbon dioxide is increased.
      • Carbon dioxide
        • Complete combustion of hydrocarbons
          • Causes the greenhouse effect and global warming
            • Hydrogen is the only petrol alternative which doesn't produce carbon dioxide.
      • Nitrogen Oxides
        • Nitrogen from the air reacts with oxygen from the air in the heat of the engine
          • Contributes to formation of photochemical smog, causing respiratory problems. Causes acid rain
            • Reduced by catalytic converters but this means carbon dioxide is increased. Also reduced in lean burn engines but this may mean unburnt hydrocarbonsare increased.
      • Sulphur Oxides
        • Sulphur in the petrol reacts with oxygen in the air in the heat of the engine
          • Causes acid rain which erodes limestone buildings and damages forests and lakes.
            • Low sulphur petrol can be produces by desulphurisation
    • Alternative fuels for Car Engine
      • Diesel
        • Not sustainable
          • Less CO produced than from petrol engine,already sold at petrol stations
            • HOWEVER Produces more NOx and particulates than a petrol engine; particulates can irritate lungs.
      • LPG or autogas
        • Not sustainable
          • Less CO, CO2, unburnt hydrocarbons and NOx than petrol engine, petrol engines easily converted
            • HOWEVER Needs to be stored under pressure so that it is liquid
      • Ethanol
        • Possibly not sustainable, large amounts of energy needed for cultivating sugar cane for fermentation
          • Less CO, SO2 and NOx than car engine; ethanol has a high octane number; sugar cane absorbs more CO2 in growth
            • HOWEVER highly flammable
      • Biodiesel
        • Can be made form waste plant and animal oil and fats so renewable but fossil fuels may be used as an energy source in production
          • Living things have absorbed CO2; it is biodegradable; less CO, CxHy, SO2 and particulatesthan from diesel engine
            • HOWEVER NOx emissions higher than a diesel engine
      • Hydrogen
        • Only sustainable if the electricity needed for electrolysis of water is from renewable source such as a solar cell.
          • Water is the only waste product of combustion
            • Highly flammable; high pressure fuel tank needed to store it as a liquid.


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