Chemistry of the atmosphere

• Describe the proportions of gases in the modern atmosphere:

  Around 80% of Nitrogen

  Around 20% of Oxygen

  Small quantities of CO2, H2O and noble gases
• Describe earth’s early atmosphere and how it was formed:

  > The earth was hot when it was formed

  > There was significant volcanic activity

  > Gases have been released from these volcanoes

  > These gases include CO2, N2, CH4, NH3, H2O
• How did the amount of oxygen in the atmosphere increase?

  > Algae and plants produced the atmospheric O2 by photosynthesis

  > As the amount of O2 gradually increased, there were more plants that produced more oxygen
• How did the amount of Carbon dioxide in the atmosphere decrease?

  > Some CO2 was dissolved in the oceans where it reacted with metal ions to form insoluble carbonates such as CaCO3

  > Some was taken in my animals to become part of a skeleton. When the animals dies, this becomes sedimentary rock

  > Some CO2 was used in photos to make oxygen
• What is the greenhouse effect. What are greenhouse gases?

  > Greenhouse gases in the atmosphere maintain temperatures on earth high enough to support life

  > They allow short wavelength radiation from the sun to pass through to the earth‘s surface but absorb the outgoing long wavelength radiation from the earth causing an increase in temp

  -> e.g water vapour, carbon dioxide, methane
• What are the potential effects of global climate change?

  > Sea level rise

  > changes in amount, timing and distribution of rainfall

  > temp and water stress form humans and wildlife

  > changes in food producing capacity of some regions

  > changes to distribution of wildlife species
• What is a carbon footprint?


  The total amont of CO2 and other greenhouse gases emitted over the full life cycle of a product, service or event
• What are the advantages of complete combustion?

  > Less soot is made

  > more heat per gram of fuel is released with complete combustion

  > poisonous carbon monoxide is not produced
• How is pollution caused by combustion?

  > When a fuel burns, the gases released to the atmosphere include carbon dioxide, water vapour, carbon monoxide, sulfure dioxide and oxides of nitrogen

  > Solid particles and unburied hydrocarbons may also be released that form particulates in the atmosphere
• What problems do particulates cause?

  > Cause global dimming by reducing the amount of sunlight that reaches the earth’s surface

  > Particulates also cause health problems for humans because of damage to the lungs
• What problems do sulfur dioxide and oxides of nitrogen cause?

  > Cause respiratory problems in humans

  > Cause acid rain which damages plants and buildings