Chemistry of the Atmosphere

avatar
Created by
Hafsa Farouk

Cards (19)

  • Carbon footprint: total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a person, company, country, product, service, or event.
    Atmospheric pollutant: harmful gases to the environment e.g. CO2, oxides of nitrogen, sulfur dioxides, CO, methane
  • Combustion: the act or process of burning - rapid oxidation accompanied by heat and, usually, light
    Particulates: solid or liquid particles suspended in the atmosphere, especially pollutants
    Acid rain: precipitation containing relatively high concentrations of acid-forming chemicals, that have been released into the atmosphere and combined with water vapor: harmful to the environment.
  • • For the last 200 million years the proportions have been:
    o 78% nitrogen
    o 21% oxygen
    o 0.9% argon
    o 0.04% carbon dioxide
  • o During the first billion years, there was intense volcanic activity that released gases forming the early atmosphere – carbon dioxide, nitrogen & small amounts of water vapour, methane & ammonia
    o The early atmosphere was very similar to Mars & Venus today – mainly CO2 & little to no O2
    o The water vapour condensed to form oceans; carbon dioxide dissolved in the water & carbonated were precipitated producing sediments on the seabed – reducing CO2 in the atmosphere
    o Comets also brought more water
  • How oxygen increased
    • Algae first evolved & produced oxygen about 2.7 billion years ago
    o After this, plants gradually evolved over 1 billion years to produce oxygen
    o Increasing the oxygen percentage to levels that enabled animals to evolve
    • Algae & plants produced oxygen by photosynthesis
  • How carbon dioxide decreased
    • Algae & plants decreased the percentage of CO2 in the atmosphere via. photosynthesis
    • CO2 also decreased from the formation of sedimentary rocks & fossil fuels that contain carbon
  • • Formation of limestone, coal, crude oil & natural gas:
    o When plants, plankton & marine animals die they fall to the seabed & get buried by layers of sediment
    o Over millions of years, they become compressed and form sedimentary rocks, oil & gas – trapping the
    carbon within then reducing levels in the atmosphere
    o Crude oil & natural gas form by deposits of plankton – forming reservoirs under the seabed
    o Coal is a sedimentary rock made from thick plant deposits
    o Limestone is a sedimentary rock, made of calcium carbonate deposits from the shells & skeletons of
    marine organisms
  • • Nitrogen was produced from volcanic eruptions and oxidation of ammonia
  • • 3 main greenhouse gases:
    o Water vapour, Carbon dioxide, Methane (20x more powerful then carbon dioxide)
  • The greenhouse effect:
    o Greenhouse gases don’t absorb short-wave radiation from the sun (UV)
    o 30% is reflected off the atmosphere back into space
    o Earth’s surface absorbs the short-wave radiation – heating it up, to cool down it emits long-wave radiation (infrared)
    o Greenhouse gases absorb the infrared radiation & re-radiate it in all directions, including back to Earth
    o The longwave radiation is thermal radiation, resulting in warming of the Earth’s surface.
  • • Actions increasing CO2
    o Deforestation – fewer trees means less CO2 is removed from the atmosphere via. photosynthesis
    o Burning fossil fuels – carbon locked up in these fuels are released as CO2 during combustion
    • Actions increasing CH4
    o Agriculture – farm animals produce methane through their digestion process
    o Creating waste – landfill sites & waste from agriculture means more methane (& carbon dioxide) are
    released due to the waste’s decomposition
  • • Potential effects of global climate change
    o Ice caps melting – causing arise in sea levels – increased flooding in coastal areas & coastal erosion
    o Change in rainfall patterns (amount, timing etc.) – may cause regions to get too much/little rain – impacting agriculture
    o Frequency & severity of storms may increase
    o Changes in temperature & water availability in habitats may affect wild species & change their distribution
  • • Actions to reduce emissions of methane & carbon dioxide
    o Use of renewable energy sources or nuclear energy instead of fossil fuels
    o Using efficient processes could conserver energy & cut waste (methane emitted from decomposition)
    o Government could tax companies/individuals based on the amount of greenhouse gases they emit
    o Government could put a cap on emissions of greenhouse gases
    o Carbon capture – captured CO2 produced by combustion before its released into the atmosphere, it can be stored underground
  • • Why actions may be limited
    o Still a lot of work to do on alternative technologies that lower CO2 emissions
    o Governments worry that economic growth may be impacted, may be bad for people’s wellbeing
    o Not everyone is on board, hard to make international agreements, countries don’t want to sacrifice
    economic gain
    o Individuals don’t want to make changes to their lifestyle – many aren’t educated on the issues
  • • The combustion of fuels is a major source of atmospheric pollutants.
    • Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur impurities.
    • The gases released into the atmosphere when a fuel is burned may include carbon dioxide, water vapour, carbon
    monoxide, sulfur dioxide and oxides of nitrogen.
    • Solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere.
  • • In complete combustion (where enough oxygen is present)
    o carbon dioxide is released but all the fuel is burnt
    • In incomplete combustion (where there is a lack of oxygen)
    o particulates of carbon (soot), unburned fuel (hydrocarbons) & carbon monoxide are released
  • • Carbon monoxide (CO) is a toxic gas
    o It binds to the haemoglobin in red blood cells stopping the transport of oxygen within the body
    o Lack of oxygen causes – fainting, coma, death
    o It is colourless and odourless and so is not easily detected
  • • Sulfur dioxide and oxides of nitrogen
    o Sulfur dioxide released during combustion of fossil fuels (they contain sulfur impurities)
    o Nitrous oxides produced by the reaction between oxygen & nitrogen in the air caused by immense heat (often in car/plane engines)
    o When these gases mix with clouds, they form dilute acids (sulfuric & nitric) – this acid rain:
    ▪ Kills plants
    ▪ Damages buildings & statues
    ▪ Corrodes metal
    o Also causes respiratory issues if breathed in
  • • Particulates
    o Cause global dimming by reflecting sunlight back into space, meaning less light reaches the Earth (decreased photosynthesis)
    o Lead to health problems for humans as they get stuck in the lungs causing respiratory issues