GCSE AQA Chemistry 1 Fuels & The Environment

GCSE AQA Chemistry 1 Fuels & The Environment

1. Crude Oil

   • Mixture of hydrocarbons
     • Fuels made of carbon & hydrogen
     • No chemical bonds - keep their original properties
       • Can separate using fractional distillation
         • Column works continuously - heated crude oil pumped in at bottom
           • Vaporised oil rises up & various fractions tapped off as they condense
   • Properties
     • Made up of hydrocarbons - alkanes
       • Chains of carbon atoms surrounded by hydrogen atoms
         • Different length chains
         • Carbon forms 4 bonds & hydrogen forms 1
       • First 4: Methane, Ethane, Propane, Butane
         • Forms as many bonds as possible - saturated
       • Shorter molecules - more runny (less viscous)
         • Shorter molecules - more volatile
           • Shorter molecules - more flammable
     • General formula: CnH2n+2
   • Uses
     • Volatilty - refinery gas - good as bottled gas
       • Petrol - higher boiling point - liquid
         • Viscous hydrocarbons - lubricants

2. Crude oil as a fuel

   • Burn cleanly so good fuels
     • Transport, central heating, power stations
   • Also provides raw materials for making chemicals - plastics
   • Alternatives are possible but things are set up for oil fractions - easier, cheaper & more reliable
   • Will run out - non-renewable fuel
     • New reserves being discovered & technology improving
     • Should start conserving & finding alternatives

3. Environmental problems

   • Burning fossil fuels
     • Power stations & cars
     • hydrocarbon + oxygen --> carbon dioxide + water vapour
       • Energy (heat) also produced
       • If fuel contains sulphur impurities - sulphur dioxide released
         • If enough oxygen - complete combustion, if not then partial
           • Soot, unburnt fuel & carbon monoxide released
             • Global Dimming - particles reflect sunlight back into Space
         • 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
   • Increasing carbon dioxide = Climate Change
     • Causes global warming, changing rainfall patterns, flooding
   • Alternative fuels being developed
     • Ethanol - plant material - biofuel from fermentation
       • Carbon neutral, engines need to be converted, stop growing crops
     • Biodiesel - vegetable oils
       • Carbon neutral, don't need to convert engines, can't make enough to replace diesel, expensive
     • Hydrogen gas - electrolysis of water
       • Clean, need special engine, not widely available, hard to store