Chemistry of the Atmosphere Flashcards
what chemicals is the earths atmosphere made of
nitrogen
oxygen
co2
water vapour
noble gases
how much of the atmosphere is made of nitrogen
80%
how much of the atmosphere is made of oxygen
20%
how much of the atmosphere is made of oxygen
20%
how long have the proportions of gases been like how they are now
for 200 million years
why is evidence of the earths early atmosphere limited
the timescale of 4.6 billion years
the earths early atmosphere theory
intense volcanic activity released gases that formed the early atmosphere
the atmosphere was like mars or venus today with mainly co2 and little or no o2
volcanes produced n2 which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia
water vapour condensed to form the oceans
co2 dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of co2 in the atmosphere
where is the oxygen currently in the atmosphere from
algae and plants produced o2 by photosynthesis
when did algae first produce oxygen
2.7 billion years ago
why did oxygen levels increase after algae produced oxygen
plants evolved
what was the result of an oxygen increase
enabled animals to evolve
how did carbon dioxide in the atmosphere decrease
algae and plants decreased the co2 in the atmosphere by photosynthesis
what other than photosynthesis decrease carbon dioxide
the formation of sedimentary rocks that contain carbon eg limestone and coal
the production of fossil fuels from the remains of dead plants and animals when they decayed
when was methane removed from the early atmosphere
once oxygen was made
when was ammonia removed from the early atmosphere
once oxygen was made
where do scientists think life first evolved from
near underwater volcanoes
what layer did oxygen form in the upper atmosphere
ozone layer
why was the ozone layer important for life on land
shield the earth from harmful uv light so organisms could leave the water
how was co2 removed in the ocean
some dissolved in ocean and was taken up by small sea creatures to form their shells
what do greenhouse gases do
maintain temperatures on earth high enough to support life
examples of greenhouse gases
water vapour
carbon dioxide
methane
describe the greenhouse effect
radiation at short wavelengths from the sun passes through the atmosphere
the earth absorbs some radiation and warms up but some heat is radiated from the earth as long wave infrared radiation
some of this infrared radiation is absorbed by greenhouse gases in the atmosphere
atmosphere warms up leading to the greenhouse effect and global warming
which human activities increase methane
raising livestock eg cows - more waste produced
decay of organic waste in landfill sites
which human activities increase carbon dioxide
driving
consuming electricity
why is it difficult to predict climate change
it is hard to understand the earths climate as it is complex and there are many variables
what is done because it is hard to understand climate change
simplified models
speculation
opinions presented in the media
that are based on only parts of the evidence
what is a major cause of climate change
an increase in global temperature
what are the potential effects of global climate change
extinction of species
rising sea levels due to melting polar ice caps
migration as people move from areas suffering drought/flooding
decrease in crop yield for all major world crops
when does global warming happen
when the greenhouse effect is enhanced as more thermal radiation is absorbed and radiated back to earth
what is carbon footprint
the total amount of co2 and other greenhouse gases emitted over the full life cycle of a product, service or event
which chemicals need to be reduced to reduce carbon footprint
reducing emissions of carbon dioxide and methane
which activities can reduce carbon footprint
using less electricity so using less fossil fuels
using an alternative source of electricity
reducing amount of travel or transportation of goods or people
planting more trees
why might carbon footprint reduction action be limited
its more difficult
can be more expensive
planting trees takes away land that could be used to grow crops
what is the combustion of fuels a source of
atmospheric pollutants
what do most fuels contain
carbon
and or hydrogen
maybe sulfur
which gases can be released into the atmosphere when a fuel burns
carbon dioxide
water vapour
carbon monoxide
oxides of nitrogen
what products other than these gases may be released when a fuel burns
solid particles
unburned hydrocarbons
which form particulates
which gases are released in incomplete combustion
soot (carbon)
carbon monoxide
unburnt fuel
what does the combustion of hydrocarbons release
energy
what happens to carbon and hydrogen in fuels during combustion
oxidised to form carbon dioxide and water
features of carbon monoxide
toxic colourless gas
odourless
not easy to detect
features of sulfur dioxide and oxides of nitrogen
cause acid rain
cause respiratory problems in humans
features if particulates
cause global dimming
human health problems
