chemistry of the atmosphere Flashcards
describe the make up of gases in the atmosphere today
78% nitrogen, 21% oxygen, 1% made up of other gases such as co2, water vapour, and noble gases eg argon
describe the make up of gases in the early atmosphere
first billion years:
intense volcanic activity, which released gases, e.g water vapour, that formed atmosphere when erupted
describe the make up of gases in the atmosphere phase 2
- as earth cooled, water vapour from volcanoes condensed to form oceans
- lots of co2 and little oxygen due to volcanoes
- some co2 dissolved into ocean, and reacted with minerals in sea to form carbonate precipitates, which formed carbonate sediments on the sea bed.
- some co2 was used to make corals and shells for organisms eg mussels. when these died, they formed limestone, which removed co2 from atmosphere
- also small amounts of nitrogen, methane, and ammonia
describe the make up of gases in the atmosphere phase 3
- photosynthetic algae started to evolve in oceans. photosynthesis produce oxygen into the atmosphere.
- over following billion years, plants evolved. oxygen increased, to the point animals could evolve.
- photosynthesis also takes in co2, co2 fell as carbon gets trapped in fossil fuels
how is coal formed
ferns and trees do not decompose in low oxygen or acidic conditions. remains compressed by layers of sediment. high temp & pressure conditions forms the coal
how is oil formed
(crude oil - organic chemistry)
how is natural gas formed
near deposits of oil, as they are formed from plankton in a similar way to oil
carbon trapped during photosynthesis released when fossil fuels are burned
what are the greenhouse gases
water vapour, co2 and methane
how does the greenhouse effect work
- sun emits short wavelength radiation SWR (eg uv, visible light)
- some is reflected, rest passes through atmosphere
- earths surface absorbs energy from radiation, and radiates long wave radiation (eg infrared)
- greenhouse gases in atmosphere do not interact strongly with SWR meaning SWR passes through it, however they do react with LWR, meaning LWR is absorbed
- energy trapped in atmosphere, causing temp to increase enough to support life
- human activity enhances greenhouse effect
how do the greenhouse gases increase
water vapour: temp of air
co2: burning fossil fuels, deforestation
methane: agriculture- paddy rice cultivation and when cattle passes wind, landfills
what can climate change lead to
- ice sheets and glaciers melt, sea levels rise, low lying floods
- more extreme weather
- affect distribution and seasonal activity of plants and animals
what is the proof & limits of proof of climate change
evidence is shared, between scientists then peer reviewed to detect false claims or validate it.
- it is complex, causing speculation in the media, where stories are biased or only based on some evidence
- difficult to accurately predict amount temperature will increase
what is carbon footprint
measure of co2 and other greenhouse gases released over the full life cycle of something
how can we reduce carbon footprint and methane
co2
- insulating or reducing heating in homes to reduce burning fossil fuels
- public transport to reduce car co2 emissions
- switch to renewable electricity sources or energy saving bulbs to reduce burning fossil fuels
methane
- eat less cow produce to reduce need for cattle
- trapping and burning for electricity rather than landfill
limitations of reducing carbon footprint and methane
- expensive & reluctance to pay
- inconvenient
- people enjoy cow produce & reluctance to stop
- expensive to trap and burn methane
what is a fuel
something that releases energy when combusted
how can a fuel release carbon into atmosphere
plenty of oxygen:
carbon & hydrogen often released, atoms oxidised in air via complete combustion as co2 produced, which contributes to greenhouse effect & climate change
limited oxygen
carbon monoxide produced rather than co2. co has no colour or smell
how can a fuel release other products into atmosphere
coal contains sulfur, which is oxidised when burned to make sulfur dioxide
engines produce nitrogen, which are oxidised in high temps to make oxides of nitrogen
affects of sulfur dioxide and oxides of nitrogen
- breathing problems
- dissolve in rainwater forming acid rain, which damaged trees and corrodes buildings
how can a fuel release particulates into atmosphere
when a truck burns diesel, clouds of particles of carbon (soot) and unburned hydrocarbon, known as particulates, are released
affects of particulates
- heart & lung disease
- causes global dimming (reduce amount of energy from sun that reaches earths surface) which can affect rainfall
