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%)

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2
Q

Why is evidence for the early atmosphere limited?

A

Because of the time scale of 4.6 billion years

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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
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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
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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.
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6
Q

What did the early atmosphere consist of?

A
  • CO2
  • virtually no oxygen
  • like mars and venus today
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7
Q

How are oceans formed?

A
  • water vapour from atmos. condenses
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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

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9
Q

What happend after plants and algae?

A

Marine animals evolved. Their shells and skeletons contained carbonates from the oceans

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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
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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
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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
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13
Q

How is coal formed?

A
  • Sedimentary rock
  • From thick plant deposits
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14
Q

How is limestone formed?

A
  • Sedimentary rock
  • Made of calcium carbonate deposits from shells/skeletons of marine organims
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15
Q

What evolved first? Algae or green plants?

A
  • Algae - 2.7bn yrs ago
  • Over the next bn yrs, green plants also evolved
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16
Q

Order of events of the theory

A
  1. Volcanoes
  2. Oceans
  3. Algae
  4. Green plants
  5. 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
Q

What does human activity produce?

A
  • Carbon dioxide
  • Methane
26
Q

What are carbon footprints?

A

total amount of carbon dioxide and other
greenhouse gases emitted over the full life cycle of a product,
service or event.

27
Q

Why is measuring the total carbon dootprint of smth be hard?

A

So many diff factors to consider - emmisions released of sourcing all the parts, using it and disposing it

28
Q

Ways to reduce carbon footprint + explain

A
  • 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
Q

Why is making reductions to the carbon footprint hard?

A
  • 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
Q

What do FF contain? What happens doing combustion?

A
  • 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
Q

What happens if there isnt enough oxyen when FF are burning?

A
  • Incomplete combustion
  • Solid particles (particulates) of soot (carbon) and unburnt fuel are released
  • Carbon monoxide produced as well as CO2
32
Q

Probs of particulates

A
  • 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
Q

CO probs

A
  • 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
Q

Whats produces when FF undergo combustion?

A
  • CO2
  • Water vapour
  • Sulfur dioxide
  • Nitrogen oxides
35
Q

What is sulfur dioxide and nitrogen oxides? What happens when they mix?

A
  • 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
Q

Probs of acid rain

A
  • Kills plants
  • Damages buildings/statues
  • Corrodes metal
  • Respiratory probs if breathed in