atmosphere

• earths early atmosphere

  mostly CO2 because of volcanic eruptions - also caused nitrogen and small proportions of methane and ammonia

  water vapour condenses to form ocean
• why did CO2 levels decrease

  more plants were taking it in for photosynthesis
• why have nitrogen levels stayed the same

  its an unreactive gas so it builds up gradually in the atmosphere
• why did oxygen levels increase

  more life on the planet and algae and plants photosynthesising
• greenhouse gas effect

  electromagnetic radiation passes through earths atmosphere

  earth absorbs most radiation and warms up

  earth radiates energy as infrared radiation

  some of the IR goes into space

  some IR absorbed by greenhouse gases in atmosphere

  atmosphere warms up leading to global warming
• what are fossil fuels burnt for

  electricity

  petrol

  farming cattle

  rice fields

  rotting landfill
• effects of climate change

  extinction of species

  raising sea levels - melting of polar ice caps

  decrease in crop yield
• carbon footprint

  total amount of CO2 and other greenhouse gasses emitted over the full life cycle of a product, service or event
• combustion

  burning a fuel in oxygen
• complete combustion

  when there's a sufficient amount of oxygen

  releases maximum amount of energy and produces CO2 and water
• combustion equation

  fuel + oxygen --> co2 and water
• balanced equation for complete combustion

  CH4 + 2O2 --> CO2 + 2h2o
• incomplete combustion

  poor amount of oxygen
• incomplete combustion equation

  hydrocarbon + oxygen --> carbon monoxide + water + carbon
• carbon monoxide

  toxic gas colourless and odourless

  binds haemoglobin in red blood cells preventing them from carrying oxygen
• sulfur dioxide and oxides of nitrogen

  cause acid rain and respiratory problems
• particulates

  cause global dimming and human health problems