c9 - chemistry of the atmosphere

• Initially Earth was covered in volcanoes which erupted and released water vapour and carbon dioxide
• water vapour condensed to form the oceans
• carbon dioxide dissolved into the oceans - produced sediments which reduced the amount of carbon dioxide in the atmosphere
• there is limited evidence for the earths early atmosphere as it was 4.6 billion years ago
• Carbon dioxide dissolved in oceans forming carbonates - precipitated as sedimentary rock
• Formation of fossil fuels which have carbon trapped within them (decrease in carbon dioxide)
• Algae and plants reduced the amount of carbon dioxide by photosynthesis
• atmosphere now - Approximately 80% nitrogen, 20% oxygen, and small amounts of gases like carbon dioxide, water vapour and noble gases
• The increase in oxygen levels in the atmosphere allowed animals to evolve
• Algae started producing oxygen 2.7 billion years ago
• Algae and plants produce oxygen in photosynthesis
• Human activity increases the amount of greenhouse gases
• Long wavelength radiation reflected back by the Earth (thermal radiation)
• Short wavelength radiation from the sun
• Agriculture - farm animals release methane
• Landfill sites release methane and CO2
• carbon footprint - A measure of the amount of greenhouse gases released over the full cycle of something
• Governments are not prepared to make radical changes, Don’t want to disrupt the economy, Some people don’t want to make changes to their lifestyle
• the footprint can be reduced by Using processes that use less energy, Using technology that captures carbon dioxide before it is released, Taxing companies based on the amount of greenhouse gases released and Using renewable energy resources
• The increasing average global temperature is a major cause of climate change
• consequences of climate change : Food production affected by changes in temperature and rainfall, Ice caps melting leads to higher sea levels, Storms become more frequent and extreme, Changes in rainfall patterns and increased flooding
• carbon dioxide; released into atmosphere through complete combustion of fossil fuels which causes climate change
• nitrogen oxides are released into the atmosphere when heated at high temperatures. they cause respiratory problems, acid rain and smog
• carbon monoxide is released through the incomplete combustion of fossil fuels. It is a toxic gas which binds to haemoglobin which carries oxygen around your body
• sulphur dioxide ; impurities in the fossil fuels burning - leads to acid rain
• carbon particulates are released through incomplete combustion and cause global dimming and respiratory problems
• difference between climate & weather?

  • weather refers to short term atmospheric conditions
  • climate describes typical weather conditions within an entire region for a very long time
• describe properties of gas in the modern atmosphere:

  • 80% nitrogen
  • 20% oxygen
  • small quantities of CO2, H2O and other noble gases
• describe earths early atmosphere & how it was formed :

  • hot, significant volcanic activity
  • gases released from volcanoes : CO2, N2, CH4, H2O
• how did the amount of oxygen in the atmosphere in the atmosphere increase?

  • algae & plants produced O2 by photosynthesis - as oxygen increased, more plants that produced more oxygen
• how did the amount of carbon dioxide in the atmosphere decrease?

  • some co2 dissolved in oceans, reacted with metal ions to form insoluble carbonates - or was taken in by animals to become part of a skeleton (then becomes sedimentary rock)
  • some CO2 used in photosynthesis
• greenhouse gases allow short wavelength radiation from the sun to pass through the atmosphere to the earths surface - absorbing the outgoing long wavelength radiation from the earth causes an increase in temperatures
• why is the greenhouse effect necessary for life?

  • natural phenomenon
  • earth would be too cold for life to exist
• what actions can be taken to reduce a carbon footprint?

  • use of alternative energy supplies
  • energy conservation
  • carbon taxes & licenses
• what are the advantages of complete combustion?

  • less soot (carbon particulates)
  • more heat per gram of fuel is released
  • carbon monoxide not produced
• how is pollution caused by combustion?

  • when fuel burns gases such as carbon dioxide, water vapour, sulphur dioxide etc released into atmosphere
  • solid particles & unburned hydrocarbons may also be released that form particulates in the atmosphere
• what are the issues regarding sulfur dioxide & oxides of nitrogen ?

  • cause respiratory problems in humans & acid rain
  • acid rain damages plants & buildings
• what problems do particulates cause?

  • global dimming by reducing amount of sunlight reaching the earths surface
  • can cause damage to lungs
• Carbon capture technology allows us to trap carbon and store it deep underground. A downside is that it is very expensive. 
• adverse effects of acid rain:

  • damages statues & buildings
  • makes soil more acidic which harms plants