Chemistry of the Atmosphere Flashcards
1
Q
what is our current atmosphere like?
A
- 79% nitrogen
- 21% oxygen
- 0.04% carbon dioxide
- <1% argon+water vapour
2
Q
earth’s early atmosphere
A
- similar to venus today
- 95% CO2
- x oxygen
- volcanic activity=nitrogen+ small amounts of ammonia/water vapour released=built up overtime
3
Q
how did CO2 levels drop?
A
- water vapour condensed=oceans formed
- most CO2 in the atmosphere dissolved in oceans
- CO2 in ocean=formed carbonate precipitates=sediments on sea bed
- green plants+algae evolved=used CO2 for photosynthesis
- marine animals evolved=shells+skeletons=carbonate from ocean
- CO2 trapped in fossil fuels+rocks when organisms died
4
Q
how are fossil fuels formed?
A
- plants, plankton, marine animals die=fall to seabed=buried by layers of sediment
- sediment compressed over millions of years=sedimentary rock, oil, gas
- crude oil+natural gas=deposits of plankton=form reservoirs under seabed when they’re trapped in rock
- coal=sedimentary rock=thick plant deposits
- limestone=sedimentary rock=calcium carbonate deposits=shells+skeletons of marine organisms
5
Q
how did oxygen levels increase?
A
- algae+plants photosynthesised=oxygen released
- algae evolved 2.7 billon years ago
- green plants evolved over the next billion years
- oxygen levels increase=more complex organisms eg. animals evolved
6
Q
what is the enhanced greenhouse effect?
A
- short-wavelength radiation hits the earth
- the earth reflects it as long-wavelength radiation
- trapped by greenhouse gases eg. methane, CO2, water vapour=insulating layer in earth’s atmosphere
- greenhouse gases re-radiates it back to earth
- earth’s warms up
7
Q
how have human activities increased greenhouse gases?
A
- deforestation=less trees=less CO2 used for photosynthesis
- agriculture=more farm animals=more methane when they digest
- creating waste=more landfill+waste from agriculture=more CO2+methane as waste decomposes
8
Q
why do we need greenhouse gases?
A
they allow earth to be warm enough to support life
8
Q
how can a carbon footprint be reduced?
A
- using renewable energy/nuclear energy
- being more efficient=conserve energy+cut waste= x decomposers=reduce methane
- govs=tax companies/people on how much greenhouse gases they emit eg taxing cars on how much CO2 they emit on a set distance=people buy more fuel-efficient=less polluting
- govs=put a cap on emissions of greenhouse gases=sell licenses for emissions up to that cap
- tech captures CO2 before released when burning fossil fuels=CO2 then stored deep underground in cracks in rocks eg. oil wells
8
Q
how does an increase in CO2 lead to climate change?
A
- most scientist agree that extra CO2 from human activity=increase in global temp=climate change
- evidence for climate change=peer reviewed
- difficult to model such complex systems as global climate change=simplified models, speculation and opinions presented in the media be based on some parts of evidence=biased
9
Q
what are the consequences of climate change?
A
- increase in global temp=ice caps melting=sea levels rise=more floods+coastal erosion
- rainfall patterns change=areas may get too much/little water=affect ability to produce food
- increase frequency+severity of storms
- changes in temp+water=affects wild species=different distribution
9
Q
what is a carbon footprint?
A
total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
10
Q
why is it hard to reduce carbon footprint?
A
- alternative tech needs to be made to lower CO2
- govs worried it will affect economic growth= bad for wellbeing especially developing countries
- hard to make international agreements to reduce emissions=countries x sacrifice economic growth if other won’t do it
- people need to change their lifestyles eg using more public transport= hard to get people to change if they don’t want to+ x enough education on why the changes are made+how to make them
11
Q
atmospheric pollutants
A
- incomplete combustion= CO, carbon particulates (soot), a little CO2 released
- soot inhaled=stuck in lungs=damage=respiratory problems & reflect light back into space=global dimming=less light reaches earth
- CO=toxic= x blood carrying oxygen=fainting, coma, death & silent killer=hard to detect ( x colour or smell)
- sulfur dioxide=released when fossil fuels that have sulfur impurities are burnt
- nitrogen oxides=released by car engines
- SO2+NO2=mix with clouds=dilute sulfuric+nitric acid=acid rain=kills plants, damages buildings+statues, corrosion of metal & respiratory problems when breathed in
