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 Fuels
                   Fuels
 A Fuel is a substance that
     produces Energy when
     burned.
 A good fuel releases it’s energy
     over a longer period of time
 A reaction in which energy is released is called an
  Exothermic reaction( a reaction in which heat is
  taken in called an Endothermic reaction).
 Another word for burning is Combustion ie.we
  combine the element with Oxygen gas
           Common fuels
 Most  common household fuels contain
  the element Carbon.
 Fuels that contain carbon and hydrogen
  only are called Hydrocarbons.
 The simplest hydrocarbon is methane
  formula CH4.Methane makes up 96%
  of Natural Gas.
       Combustion of Hydrocarbons
Combustion                                          Carbon
of Methane                                          dioxide is
gas                                                 collected in the
                                                    tube here. The
                                                    test for CO2 is
                                                    that it turns
                                                    limewater
                                                    Milky(or
                   Water vapour from the burning    chalky)
                   methane gas condenses here

             All Hydrocarbons burn to give CO2 and H2O

       Any substance that contains Carbon and Hydrogen
               gives CO2 and H2O when burned
                        Fossil Fuels
Fossil Fuels formed from living things millions of years ago.
There are three main Fossil Fuels

Coal                       Oil                        Gas
Coal was formed by         Oil was formed by dead     Gas was formed in
the decay of               sea creatures falling to   much the same
vegetation which           the sea-bed where they     way as Oil. It is
was subjected to heat      were subjected to          often collected
and pressure over a        chemical change by         when drilling for
very long period of        bacteria.                  oil.
time.

 Fossil Fuels are Finite          Alternative sources of energy which
 Fuels ie they will run           are Renewable must be found eg
 out in the future and            Solar, Wind Tide and Wave Power.
 cannot be regenerated.
        Distillation of Crude Oil
                        Crude Oil is a mixture of Substances
                        called Fractions.
                        To separate the fractions we heat them
                        until they boil off. This is known as
                        Fractional Distillation

                        The smaller fractions ie short carbon
                        chains have smaller Boiling Pts. and
                        boil off first.
                        The smaller fractions are more
                        flammable, lighter in colour and less
                        Viscous than the longer chain
A Fractionating Tower   Fractions
                       Air Pollution
   When Carbon burns in plentiful supply of air it
    produces CO2 C + O2             CO2

    When Carbon burns in an insufficient supply of
    oxygen it produces C + O2              CO `
                                                      Carbon Monoxide
                                    CO is an odourless, poisonous gas which
      The test for
                                    prevents the blood absorbing Oxygen is
      CO2 is that it
                                    therefore extremely dangerous
      turns
      limewater
      milky(chalky)
                        CO2 extinguishes fires, whereas CO burns
                        with a blue flame. CO is neutral whereas,
                        CO2 is Acidic
                 Pollution from Cars
    The main pollutants from car exhausts are
    Unburned Hydrocarbons
    Carbon Monoxide
    Oxides of Nitrogen          Cars have Catalytic
            occurs in the Spark        Converters fitted to
            Plugs of petrol cars       change these to
            (not Diesel since they     harmless gases CO2
                                       and N2. Catalytic
            do not have spark plugs)
                                       converters are metal
Sulphur from petrol produces the       honeycombs coated
acidic gas Sulphur Dioxide(also a      in Platinum
pollutant)when burned

				
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posted:8/18/2012
language:English
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