Unit 9 - Chemsitry Of The Atmosphere Flashcards
What is the composition of gases in our atmosphere now
-approx 80% nitrogen
-approx 20% oxygen
-small amounts of other gases each making up less then 1% of the atmosphere including carbon dioxide, noble gases and water vapour
Why have theories about earths early atmosphere changed and developed
-evidence is limited from such a long time period and it was so long ago
Phase 1 of earths early atmosphere (volcanoes)
-during the first billion years of earths existence there was intense volcanic activity that released gases that formed earths early atmosphere
-water vapour was released and that condensed to form oceans
-earths early atmosphere may have been similar to Mars and Venus consisting of mainly carbon dioxide with little or no oxygen gas
-volcanoes also produced nitrogen which gradually built up and there may have been small proportions of methane and ammonia
Phase 2 of early atmosphere (oceans )
-earth cooled down and so water vapour condensed to form oceans when oceans formed carbon dioxide dissolved in water and carbonates were precipitated producing sediments reducing the amount of carbon dioxide in atmosphere
Phase 3 (how oxygen increased )
-as well as absorbing the carbon dioxide in the atmosphere, green plants and blue green Algae produced oxygen by photosynthesis
-algae first produced oxygen about 2.7 billion years ago and soon after in appeared in the atmosphere
-over next billion years plants evolved and the percentage of oxygen gradually increased and this enabled animals to evolve
-oxygen then reacted with ammonia to produce ammonia and methane
How did carbon dioxide decrease (to do with fossil fuels and rocks)
-when plants, plankton and marine animals die they fall to the sea bed and get buried by layers of sediment
-over millions of years they became compressed and formed sedimentary rock, oil and gas
-aqueous chemistry begins and this locked up the carbon within them
-coal, crude oil and natural gas are made by this process and are called fossils fuels that contain carbon
Composition of gases in earths early atmosphere
-74% water vapour
-12% carbon dioxide
-5% nitrogen
-9% other gases
When was earth formed (how many years)
4.7 billion years ago
What do greenhouses gases do and give examples
-they maintain temperatures of earth high enough to support life
-water vapour, carbon dioxide and methane are examples
What is the greenhouse effect
-sun emits short wavelength radiation to the earth
-this is remitted from the surface as longer wavelength thermal radiation
-this longer wavelength EM radiation is absorbed by greenhouse gases in the atmosphere (methane, water vapour, carbon dioxide)
-this traps the energy and increase the temperature
What human activities contribute to an increase in greenhouse gases in the atmosphere
-deforestation (fewer tress means less CO2 is removed from atmosphere)
-burning fossils fuels (carbon dioxide that was locked up in these fuels are released as CO2)
-cattle farming produces methane from the cows farting
Theories to do with climate change
-based on peer reviewed evidence, many scientists believe that human activities will cause the temperature of the earths atmosphere to increase at the surface and this will increase global climate change
-however it is difficult to model such complex systems as global climate change
-this leads to simplified models, speculation and opinions presented in the media that may be based on only parts of evidence and which may be biased
Name 4 potential effects of global climate change
-increase in global temperature may lead to polar ice caps melting causing a rise in sea levels so flooding of low lying land
-more extreme weather as increased amount of energy in atmosphere this would lead to increased frequency of humanitarian disasters
-changes to rainfall patterns as temperature change alters the flow of air around atmosphere this could make it difficult to grow food due to desertification in some areas and increased rainfall elsewhere
-changes to ecosystems due to temperature and rainfall affecting the ability of organisms to survive this could lead to extinction, reduction of biodiversity
What is the carbon footprint
-Total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a produce, service or event
-it can be reduced by reducing emissions of carbon dioxide and methane
Ways to reduce carbon dioxide and methane emissions
-phase out the use of fossil fuel power sustain and switch renewable energy like solar and wind
- there is technology such as carbon ça outre and storage that can capture that carbon dioxide and store it deep underground
-reduce meat consumption or eat locally
-insulation to reduce the heating requirements /turning off lights
Why is making reduction to carbon footprint/ emissions difficult
-there still a lot of work to be done on alternative technologies that result in lower CO2 emissions
-lots of governments are worries about making changes to reduce emissions that have an impact on economic growth
-hard to get people to make changes if they don’t want to and if there’ isn’t enough education provided about why changes are necessary
Ways you can individually reduce your carbon footprint
-choosing to cycle or walkinstead of using a car
-reducing how much air travel you use
-doing anything that saves energy at home (turning heating down)
What can be released in incomplete combustion
-solid particles (particulates) made up of soot (carbon )
-carbon monoxide
Problems with carbon particulates
-if inhaled they can get stuck in the lungs and cause damage
-they also reflect the sunlight back into space this mean less light reaches the earth which causes global dimming
Problems with carbon monoxide
-toxic gas
-colourless and odourless so is not easily detected
-binds to haemoglobin in the blood so less oxygen is transported around your body which can lead to fainting
Problems with sulfur dioxide and nitrogen oxides
-when these gases mix with water in the clouds they form dilute sulfuric acid or dilute nitric acid
-this can then fall as acid rain
-acid rain kills plants and damages buildings
-also cause respiratory problems for humans
How is sulfur dioxide produced
During the combustion of fossils fuels such as coal, that contain sulfur impurities, the sulfur in the fuel become oxidised
How nitrogen oxides is produced
From a reaction between the nitrogen and oxygen in the air caused by the heat of burning cars (in the engines)
Test you can use to detect sulfur impurities in a fuel
-bubbling the gases from combustion through universels I dictator solution
-if fuel contains sulfur the gases will contain sulfur dioxide which will form sulfuric acid
-so the universal Indicator will turn red
