pollutants from fuels

• a major source of atmospheric pollutants is the combustion of fuels (i.e. coal and hydrocarbons)
• most fuels, including carbon and hydrocarbons, contain carbon and/or hydrogen and may also contain some sulfur

  these react with oxygen in the air (oxidised)
• complete combustion:

  when there is plenty of oxygen

  products = carbon dioxide + water

  carbon dioxide is a greenhouse gas, so contributes to climate change
• incomplete combustion:

  reduced/limited amount of oxygen

  products = carbon monoxide + water
• carbon monoxide is a toxic gas

  it is colourless and odourless = not easily detected
• some fuels, i.e. coal, contain the element sulfur

  when burned, the sulfur atoms are oxidised

  = sulfur dioxide
• oxides of nitrogen are produced inside engines

  the high temperatures cause nitrogen and oxygen from the air to react with oxygen

  = range of different molecules
• sulfur dioxide and oxides of nitrogen:

  • cause respiratory problems in humans
  • acid rain = damaging trees and buildings (made from limestone)
• solid particles of carbon (soot) and unburned hydrocarbons can be released forming particulates

  this is formed when burning fossil fuels due to incomplete combustion caused by insufficient oxygen

  they can cause health problems for humans (e.g. increase risk for heart and lung disease)

  and cause global dimming - reducing the amount of sun that reaches the earth surface which can affect rainfall patterns
• catalytic converters:

  • convert carbon monoxide to carbon dioxide
  • convert nitrogen oxides (which cause acid rain) to nitrogen and oxygen
  • so they reduce acid rain, global dimming, carbon monoxide
  • made up of transition metals