Chemistry of the Atmosphere - Y11 Flashcards
1
Q
For about how many years has the atmosphere reached a composition similar to what it is today? What gases are there in what percentages?
A
For 200 million years
80% nitrogen
20% oxygen
small proportions of various other gases like co2, water vapour and noble gases (less than 1%)
2
Q
Why is evidence for the early atmosphere limited?
A
Because of the time scale of 4.6 billion years
3
Q
Explain a theory about how the Earth came into existence
A
- During the first billion yrs of Earth’s existence, there was intense volcanic activity
- This released gases that formed early atmosphere
- and water vapour - condensed to oceans
- atmosphere may have been like atmos in Mars and Venus today
- consisting of mainly co2 with little/no oxygen
4
Q
What did volcanoes produce? other stuff?
A
- Nitrogen which gradually built up the atmos.
- Water vapour and CO2
- may have been small prop of methane and ammonia
5
Q
How were sediments formed on the seabed?
A
- Lots of CO2 removed from early atmos.
- as it dissolved in the oceans
- dissolved co2 went through a series of reactions to form carbonate precipitates
- that formed sediments
- Reduced co2 in the atmos.
6
Q
What did the early atmosphere consist of?
A
- CO2
- virtually no oxygen
- like mars and venus today
7
Q
How are oceans formed?
A
- water vapour from atmos. condenses
8
Q
How did the co2 level slowly decline?
A
Green plants and algae abosrbed some co2 to photosynthesis which eventually led to more complex life forms
9
Q
What happend after plants and algae?
A
Marine animals evolved. Their shells and skeletons contained carbonates from the oceans
10
Q
What happend to some of the carbon the organisms took in the atmos and oceans?
A
- Became locked up in rocks and fossil fuels
- after they died
11
Q
What happens when plants, plankton and marine animals die?
A
- fall to the seabed
- get buried by layers of sediment
- become compressed over millions of yrs
- form sedimentary rocks, oil and gas
- trapping carbon within them, to keep C level in atmos. reduced
12
Q
How is crude oil and natural gas formed?
A
- From deposits of plankton
- FF like these form reservoirs under the seabed when they get trapped in rocks
13
Q
How is coal formed?
A
- Sedimentary rock
- From thick plant deposits
14
Q
How is limestone formed?
A
- Sedimentary rock
- Made of calcium carbonate deposits from shells/skeletons of marine organims
15
Q
What evolved first? Algae or green plants?
A
- Algae - 2.7bn yrs ago
- Over the next bn yrs, green plants also evolved
16
Q
Order of events of the theory
A
- Volcanoes
- Oceans
- Algae
- Green plants
- Animals
17
Q
How old is the earth?
A
4.6bn
18
Q
What are greenhouse gases?
A
- They maintain temp on Earth high enough to support life
- Water vapour, CO2 and methane
19
Q
What do gg absorb and dont absorb?
A
- Absorbs long wanelength radiation that gets reflected back off the Earth
- Doesnt absorb incoming short wavelength radiation from the sun
20
Q
What is the greenhouse effect?
A
- Absorbs long wavelength radiation
- reflects it back off the Earth
- Re-radiation it in all directions (also back towards the Earth)
- Longwave radiation is thermal radiation
- Results in warming of the surface of the Earth
21
Q
What human acitvity affects the amuont of GG in the atmos?
A
- Deforestation - fewer trees, less co2 absorbed by photosynthesis
- Burning of FF - carbon that was locked up in these fuels is released as CO2
- Agriculture - farm animals release methane in their digestive processes
- Creating waste - more landfill sites, more waste from agriculture, more CO2 and methane from decomopostion
22
Q
Why is evidence peer-reviewed?
A
To make sure its reliable
23
Q
Why is it hard to fully understand the Earths climate?
A
- So complex - so many variables, that its very hard to make a model that isnt oversimplified
- Has led to speculation in the media - stories may be biased/ some info given only
24
Q
Consequences of climate change
A
- Polar ice caps melting - rise in sea levels, increased flooding in coastal areas and coastal erosion
- Changes in rainfall patterns - may cause some regions to get too much/little.
- Changes in temp - affects production of food
- Frequency and severity of stroms increase
- Changes in distribution of wild animals due to temp and water in a habitat
25
What does human activity produce?
* Carbon dioxide
* Methane
26
What are carbon footprints?
total amount of carbon dioxide and other
greenhouse gases emitted over the full life cycle of a product,
service or event.
27
Why is measuring the total carbon dootprint of smth be hard?
So many diff factors to consider - emmisions released of sourcing all the parts, using it and disposing it
28
Ways to reduce carbon footprint + explain
* **Renewable energy sources or nuclear energy** instead of fossil fuels
* **Using more efficient processes could conserve energy and reduce waste** - waste decomposes to release methane
* **Gov could tax companies based on the amount of gg used** like taxing cars based on the co2 they emit
* **Gov can put a cap on emissions of all gg companies make** - then sell licenses for emissions up to that cap
* **Tech that captures Co2 when burning FF** - stored deep underground in cracks in the rock like old oil wells
29
Why is making reductions to the carbon footprint hard?
* Lot of gov worry that making these changes will impact economic growth - bad for ppl wellbeing - vital in developing countries
* Hard to make international agreements - most countries dont want to sacrifice economic development if they think others wont do the same
* Individuals in developed countries need to change lifestyle - hard if they dont want to + not enough education to explain why and how they are needed
30
What do FF contain? What happens doing combustion?
* Contain hydrocarbons
* Carbon and H are oxidised so CO2 and water vapour are released to atmos.
* When there is lots of oxygen, all fuel burns - complete combustion
31
What happens if there isnt enough oxyen when FF are burning?
* Incomplete combustion
* Solid particles (**particulates**) of soot (carbon) and unburnt fuel are released
* Carbon monoxide produced as well as CO2
32
Probs of particulates
* If inhales, stuck in lungs - cause damage - leads maybe to respiratory probs
* Bad for environment - help to produce clouds that reflect sunlight back into space = means less light reaches earth causes global dimming
33
CO probs
* Stops blood caryying oxygen
* By binding to haemoglobin in blood that carries o2, less transported to body
* Lack of O2 - fainting, coma, death
* Has no smell/colour, hard to detect
34
Whats produces when FF undergo combustion?
* CO2
* Water vapour
* Sulfur dioxide
* Nitrogen oxides
35
What is sulfur dioxide and nitrogen oxides? What happens when they mix?
* SO2 - contains sulfur impurities - the sulfur in the fuel becomes oxidised
* Nitrogen oxides - created from reaction between N and O in the air, caused by heat of burning
* Mixes with clouds, they form dilute sulfuric acid/dilute nitric acid - falls as acid rain
36
Probs of acid rain
* Kills plants
* Damages buildings/statues
* Corrodes metal
* Respiratory probs if breathed in
37
Why is there less water vapour in the atmos now
Atmos is cooler now so water vapour condensed to form oceans
38
why is there less carbon dioxide in atmos now
photosynthesis in plants and dissolved to form carbonates
39
2 ways co2 has reduced
photosynthesis and co2 dissolvingin sea
40
how does a propene molecule form a polymer
double bonds break, propene molecules undergo addition polymerisaiton, forms chain polypropene
41
how is co2 released from limestone?
limestone formed by calcium carbonate which decomposes
42
how did continents form?
tectonic plates and earth cooled forming supercontinents
43
why did volcanoes reduce
earth cooled forming a crust
44
how did nitrogen form
amminoa is early earth reacting with oxygen/ dentrifying bacteria
45
How do greenhouse gases like methane cause the planet to become warmer?
* methane allows short wavelength radiation to pass through from the sun
* is re-emitted from the surface as long wavelength radiation
* which is absorbed by methane in the atmosphere
46
What increases the amount of methane
* growing rice
* farm animals like cows
* landfills
47
Why do high temperatures cause rising sea levels?
* melting of polar ice caps
* water expansion
48
What has happened to the co2 in the earths early atmosphere?
* photosynthesis iin plants
* dissolves in oceans
* used to form the shells of marine organisms
* locked up as limestone/carbonates
* locked up as fossil fuels/oil/coal
49
Explain how reducing the amount of sulfur in fossil fuels reduced the erosion of limetstone
* sulfure reacts with oxygen to form sulfur dioxide
* so less acid rain
* so less acid rain reacts with limestone
50
explain why oxides of nitrogen are formed in car engines
* engines have a high temp
* nitrogen reacts with oxygen
51
what has caused co2 to increase over the years - 2
* deforestation
* transport
52
How does limestone in a power station remove sulfur dioxide
forms calcium carbonate
53
what is locked up co2
co2 thats stored in a form that prevents it from being releasedback into the atmos
54
2 impacts of global warming
Flooding and habitat loss
55
Impacts of air pollution
* global warming - rise of sea levels - loss of habitats + food
* Acidic gases like sulfur dioxide - damage leaves, less photosynthesis, damage to lungs - asthma, affects ions in the soil
* carbon monoxide combined with haemoglobain - less O2 carried
* soot - blocks light, less photosynthesis, less glucose + damage to lungs
56
Impacts of water pollution
* Sewage - bacteria multiply, use O2 to respire, water animals cant respire, pathogens in water
* fertiliser - algae multiply, block light so plants cants photosynthesis, fish die, no O2
* Plastic - entrap animals + internal damage if swallowed,
* Acid rain - lowers pH of water, damages fish gills
57
How is natural gas formed?
* plankton dies
* and were covered by sediments
* and subjected to high temp AND high pressure
58
Why did nitrogen increase in the past/
volcnaic activity
59
Why is it improtant that cars have no sulfur impurities?
because sulfur impurities produce sulfur dioxide which causes acid rian
60
Why is solar energy more sustainable than burning oil
its renewable
61
