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chem spec > chemistry of the atmosphere > Flashcards

chemistry of the atmosphere Flashcards

1
Q

what has been roughly the same for 200 million years

A

the proportion of different gases in the atmosphere

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2
Q

proportions of gases in the atmosphere

A
  • around 80% nitrogen
  • around 20% oxygen
  • small proportions of other gases including carbon dioxide, water vapour and noble gases e.g., argon
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3
Q

why is evidence for the early atmosphere limited

A

because of the time scale of 4.6 billion years, meaning there’s a lack of evidence

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4
Q

theory about volcanic activity

A

during first billion years of earth’s existence, was intensive volcanic activity that released gases forming early atmosphere and water vapour that condensed to form oceans

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5
Q

what does the volcanic activity theory state about the start of the period of the earth’s existence

A

the earth’s atmosphere may have been like the atmospheres of mars and venus today; mainly carbon dioxide with little or no oxygen

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6
Q

what does the volcanic activity theory state about volcanoes producing [ ]

A

volcanoes produced nitrogen which built up in the atmosphere and there may have been small proportions of methane and ammonia

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7
Q

what does the volcanic activity theory propose about when the oceans formed

A

carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere

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8
Q

how did oxygen increase

A

algae and plants first produced oxygen about 2.7bil years ago, and produced the oxygen that is now in the atmosphere by photosynthesis

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9
Q

how did carbon dioxide decrease

A
  • algae and plants decreased percentage of CO2 by photosynthesis
  • decreased by formation of sedimentary rocks and fossil fuels that contain carbon
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10
Q

how did the sedimentary rocks that decreased carbon dioxide levels form

A

as water vapour from volcanoes condensed to form oceans, some co2 dissolved in oceans to form weak acid which reacted with minerals in the sea to form precipitates that formed sediments of carbonate rock on the seabed over time

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11
Q

how did the limestone that decreased carbon dioxide levels form

A

some of the co2 dissolved in the sea which was used to make corals and shells of aquatic organisms like mussels. when these organisms died, they formed limestone

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12
Q

how did the coal in the early atmosphere form

A

formed from remains of ferns and trees; died in marshy wetlands; no oxygen present so do not decay; plant remains covered in sediment and compressed; high temps and pressures cause coal to form

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13
Q

how did the crude oil in the early atmosphere form

A

formed from plankton; no oxygen present so do not decay; get trapped under sediment; heat and sediment cause them to form crude oil

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14
Q

how did the natural gas in the early atmosphere form

A

found near deposits of oils because it is formed from plankton in a similar way to oil

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15
Q

what happened as green plants evolved

A

co2 levels decreasing and oxygen levels increasing to the degree that animals were able to survive and evolve

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16
Q

what do greenhouse gases in the atmosphere do

A

they maintain temperatures on earth high enough to support life

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17
Q

name the greenhouse gases

A

water vapour, carbon dioxide and methane

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18
Q

explain how greenhouse gases maintain temperature on our planet

A
  • short wave radiation passes through atmosphere
  • earth’s surface re-emits it as long wave radiation
  • long wave radiation is absorbed by greenhouse gases which heats the planet up
19
Q

2 human activities that increase the level of CO2

A
  • burning fossil fuels for electricity as they release locked up carbon
  • deforestation, as cutting down trees reduces the amount of CO2 absorbed from the atmosphere by photosynthesis
20
Q

2 human activities that increase the level of methane

A
  • cattle reared for humans to eat produce methane
  • increase in the number of rice paddy fields
21
Q

what do many scientists believe about human activities

A

based on peer-reviewed evidence, human activities will are believed to cause the temperature of the earth’s atmosphere to increase at the surface, resulting in global climate change

22
Q

why is their bias surrounding climate change

A

global climate change is a complex system which is difficult to model. this leads to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence

23
Q

what is a major cause of climate change

A

an increase in average global temperature

24
Q

potential effects of global climate change

A
  • flooding; temp increasing means polar ice caps melt, sea levels rise, and flooding of land
  • extreme weather; more common and severe, like storms, which causes damage
  • changes in rainfall; damage crops, lack of rain causes drought, affects food production
  • extinction; if climate changes quickly, animals and plants cannot adapt to environment quick enough so will die out
25
Q

consequences of global climate change

A
  • rising sea levels as glaciers melt bc of high temperatures, causing flooding in low-lying countries
  • extinction of species due to the destruction of natural habitats
  • migration of species as they will move to areas that are more habitable (no droughts)
  • spread of diseases caused by warmer climate
  • loss of habitat due to climate change (animals that live on glaciers)
  • more droughts and wildfires
  • warmer oceans; affects sea life
  • stronger storms
26
Q

define carbon footprint

A

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

27
Q

simply, how can the carbon footprint be reduced

A

by reducing emissions of carbon dioxide and methane

28
Q

methods for reducing carbon footprint

A
  • co2 emissions reduced by using renewable energy supplies instead of fossil fuels
  • use public transport instead of private cars
  • reduce consumption of meat
  • buy locally sourced foods to reduce food mileage
  • switching to electric vehicles
  • recycling and reusing materials
29
Q

why are actions for reducing carbon footprint potentially limited

A
  • resistance on an individual level as people don’t tend to want to change their ways
  • lack of investment schemes
  • alternative technologies are still in their infancy
  • governments tend to be slow to act on issues as they fear negative impact on their economies
30
Q

what is a major source of atmospheric pollutants

A

the combustion of fuels

31
Q

what do most fuels contain

A

carbon and/or hydrogen, and may also contain some sulfur

32
Q

what can also be released in combustion reactions

A

solid particles and unburned hydrocarbons that form particulates in the atmosphere

33
Q

what are the gases released into the atmosphere when a fuel is burned

A

may include carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen

34
Q

what is complete combustion

A

there is enough oxygen in the reaction, so carbon dioxide is produced

35
Q

why is the complete combustion of fuels bad

A

carbon dioxide is produced, which is an atmospheric pollutant as it is a greenhouse gas that contributes to climate change

36
Q

why is the incomplete combustion of fuels bad

A

because carbon monoxide is produced, which is a toxic gas that is colourless and odourless, meaning it’s not easily detected; reduces body’s ability to carry blood

37
Q

products of complete combustion

A

carbon dioxide + water

38
Q

products of incomplete combustion

A

carbon monoxide + water

39
Q

how is sulfur dioxide produced from fuels

A

some fuels such as coal contain sulfur impurities, and, when the fuel is burned, the sulfur atoms are oxidised to produce sulfur dioxide gas

40
Q

how are oxides of nitrogen produced from fuels

A

they are produced inside engines because the temps and pressures are so high that the nitrogen and oxygen in the air react together to form nitrous oxides

41
Q

why is sulfur dioxide and oxides of nitrogen bad

A

they can cause respiratory problems in humans and cause acid rain; destroys trees, kills fish, corrodes buildings made of limestone

42
Q

how are particulates (soot) produced from fuels

A

incomplete combustion

43
Q

why are particulates bad

A

they cause global dimming and health problems for humans e.g., lung cancer, asthma attacks

chem spec (12 decks)

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