combustion reactions and pollution

• what is complete combustion?

  sufficient oxygen

  carbon dioxide and water products
• what is the general equation for complete combustion?

  alkane + oxygen --> carbon dioxide + water
• what is incomplete combustion?

  insufficient oxygen

  products are carbon monoxide/carbon and water
• what are the general equations for incomplete combustion?

  alkane + oxygen --> carbon monoxide + water

  alkane + oxygen --> carbon + water
• what does carbon cause?

  global dimming
• what does carbon monoxide cause?

  toxic - breathing problems (asthma)
• what does fuel in a car engine produce?

  1. carbon dioxide
  2. carbon monoxide
  3. nitrogen oxides
  4. unburned hydrocarbons
  5. sulfur dioxide
• what is a catalytic converter used for?

  removes pollutant gases from car engine
• what are the equations for catalytic converters?

  2CO + 2NO --> N2 + 2CO2

  C8H18 + 25NO --> 12.5O2 + 18CO2 + 9H2O
• what are the equations for the combustion of sulphur impurities?

  S + O2 --> SO2 (burning oil in power stations)

  CH3SH + 3O2 --> CO2 + 2H2O + SO2 (burning hydrocarbons in engine)

  SO2 + 0.5O2 --> SO3 (UV provides energy for reaction)
• why are sulfur oxides dangerous?

  Sox is soluble in water and reacts to form acidic solutions, causes acid rain
• what does combustion of sulphur impurities cause?

  SO2 being released into atmosphere
• how is O2 prevented from going into atmosphere?

  flue gases as they pass up chimney via flue-gas desulfurisation
• what are the equations for flue-gas desulfurisation?

  CaCO3 --> CaO + CO2

  CaO + SO2 --> CaSO3
• how are greenhouse gases produced?

  1. UV and visible radiation from sun absorbed by Earth
  2. emitted at longer wavelengths
  3. infrared radiation is absorbed as molecules in atmosphere
  4. reradiate energy
• what are examples of greenhouse gases?

  1. carbon dioxide
  2. water vapour
  3. methane