C9 - chemistry of the atmosphere

Question 1

what happened in the first phase of earth’s history (according to the most common theory)?

Answer 1

volcanoes erupted and gave out gases

Question 2

how do we think the early atmosphere was formed?

Answer 2

from volcanoes erupting and releasing lots of gases

Question 3

what was the early atmosphere like?

Answer 3

it was probably mostly carbon dioxide, with virtually no oxygen. This is quite like the atmospheres of Mars and Venus today

Question 4

what gases do volcanoes release?

Answer 4

mostly nitrogen, but also water vapour and small amounts of methane and ammonia

Question 5

how did nitrogen get in the atmosphere?

Answer 5

volcanic activity released nitrogen, which built up in the atmosphere over time

Question 6

according to one theory, what happened in the second phase of Earth’s history?

Answer 6

oceans, algae and green plants absorbed carbon dioxide

Question 7

how were the oceans formed? In what phase of the earth’s history did this happen?

Answer 7

oceans were formed when the water vapour in the atmosphere condensed, and this happened in the second phase

Question 8

how was carbon dioxide removed from the atmosphere?

Answer 8

1. lots of carbon dioxide was removed from the early atmosphere as it dissolved in the oceans. This dissolved carbon dioxide then went through a series of reactions to form carbonate precipitates that formed sediments on the seabed.
2. green plants and algae evolved and absorbed some of the carbon dioxide so that they could carry out photosynthesis. Later, marine animals evolved. Their shells and skeletons contained carbonates from the oceans
3. some of the carbon these organisms took in from the atmosphere and oceans became locked up in rocks and fossil fuels after the organisms died

Question 9

what happens when plants, plankton and marine animals die?

Answer 9

they fall to the seabed and get buried by layers of sediment. over millions of years, they become compressed and form sedimentary rocks, oil, and gas - trapping the carbon within them and helping to keep carbon dioxide levels in the atmosphere reduced

Question 10

what is the name for things like coal, crude oil and natural gas that are made when plants, plankton and marine animals die?

Answer 10

fossil fuels

Question 11

what are crude oil and natural gas formed from?

Answer 11

deposits of plankton

Question 12

what do crude oil and natural gas do when they are trapped in rocks?

Answer 12

they form reservoirs under the seabed

Question 13

what is coal?

Answer 13

a sedimentary rock made from thick plant deposits

Question 14

what type of rock is limestone?

Answer 14

sedimentary

Question 15

what is limestone made of?

Answer 15

calcium carbonate deposits from the shells and skeletons of marine organisms

Question 16

according to one theory, what happens in the third phase of the Earth’s history?

Answer 16

green plants and algae produce oxygen

Question 17

which plant evolved first? how long ago did it evolve?

Answer 17

algae evolved first, about 2.7 billion years ago

Question 18

what effect did photosynthesis have on the development of life?

Answer 18

it caused oxygen levels to build up in the atmosphere over time, so that more complex life (like animals) could evolve

Question 19

how long ago did the atmosphere reach a composition similar to what it is today?

Answer 19

about 200 million years ago

Question 20

what is the composition of the atmosphere today?

Answer 20

approximately 80% nitrogen, 20% oxygen and small amounts of other gases (each only makes up less than 1% of the atmosphere), mainly carbon dioxide, noble gases and water vapour

Question 21

what allows the earth to be warm enough to support life?

Answer 21

greenhouse gases like carbon dioxide, methane and water vapour, which act like an insulating layer in the Earth’s atmosphere

Question 22

what is the greenhouse effect?

Answer 22

all particles absorb certain frequencies of radiation. Greenhouse gases don’t absorb the incoming short wavelength radiation from the sun - but they do absorb the long wavelength radiation that gets reflected back off the earth. The longwave radiation is thermal radiation, so it results in warming of the surface of the earth. This is the greenouse effect.

Question 23

name 4 forms of human activity that affect the amount of greenhouse gases in the atmosphere?

Answer 23

1. deforestation
2. burning fossil fuels
3. agriculture
4. creating waste

Question 24

how does deforestation affect the amount of greenhouse gases in the atmosphere?

Answer 24

fewer trees means less CO2 is removed from the atmosphere via photosynthesis

Question 25

how does burning fossil fuels affect the amount of greenhouse gases in the atmosphere?

Answer 25

carbon that was 'locked up' in these fuels is released as CO2

Question 26

how does agriculture affect the amount of greenhouse gases in the atmosphere?

Answer 26

more farm animals produce methane through their digestive processes

Question 27

how does creating waste affect the amount of greenhouse gases in the atmosphere?

Answer 27

more landfill sites and more waste from agriculture means more CO2 and methane released by decomposition of waste

Question 28

why is it hard to fully understand the Earth's climate?

Answer 28

it's so complex, and there are so many variables, that it's very hard to make a model that isn't oversimplified

Question 29

describe 4 ways climate change could have dangerous consequences

Answer 29

1. an increase in global temperature could lead to polar ice caps melting - causing a rise in sea levels, increased flooding in coastal areas and coastal erosion 2. changes in rainfall patterns (the amount, timing and distribution) may cause some regions to get too much or too little water. This, along with changes in temperature, may affect the ability of certain regions to produce food 3. the frequency and severity of storms may also increase 4. changes in temperature and the amount of water available in a habitat may affect wild species, leading to differences in their distribution

Question 30

what are carbon footprints?

Answer 30

a measure of the amount of carbon dioxide and other greenhouse gases released over the full life cycle of something.

Question 31

why can it be really difficult to measure the total carbon footprint of something?

Answer 31

there are many different factors to consider - for example, you would have to count the emissions released as a result of sourcing all the parts, and in making it, not to mention the emissions produced when you actually use it and finally dispose of it

Question 32

why can a rough calculation of carbon footprints be useful?

Answer 32

it can give a good idea of what the worst emitters are, so that people can avoid them in future

Question 33

describe 5 things that can be done to reduce a carbon footprint

Answer 33

1. renewable energy sources or nuclear energy could be used instead of fossil fuels 2. using more efficient processes could conserve energy and cut waste. Lots of waste decomposes to release methane, so this will reduce methane emissions 3. governments could tax companies or individuals based on the amount of greenhouse gases they emit 4. there's also technology that captures the CO2 produced by burning fossil fuels before it's released into the atmosphere - it can then be stored deep underground in cracks in the rock such as old oil wells

Question 34

why is reducing carbon footprints difficult?

Answer 34

1. there's still a lot of work to be done on alternative technologies that result in lower CO2 emissions 2. a lot of governments are also worried that making these changes will impact on the economic growth of communities - which could be bad for people's well-being, especially for countries that are still developing 3. because not everyone agrees, it's hard to make international agreements to reduce emissions. Most countries don't want to sacrifice their economic development if they think that other's won't do the same 4. individuals in developed countries need to make changes to their lifestyle, but it's hard to get people to make changes if they don't want to and if there isn't enough education provided about why the changes are necessary and how to make them

Question 35

why does burning fossil fuels release carbon dioxide and water vapour into the atmosphere?

Answer 35

fossil fuels, such as crude oil and coal, contain hydrocarbons. During combustion, the carbon and hydrogen in these compounds are oxidised, which releases carbon dioxide and water vapour

Question 36

what is produced by the incomplete combustion of fossil fuels?

Answer 36

during incomplete combustion, some of the fuel doesn't burn. This means that solid particles (called particulates) of soot (carbon) and unburnt fuel are released and carbon monoxide can be produced as well as carbon dioxide

Question 37

what problems can particulates in the air cause?

Answer 37

- if particulates are inhaled, they can get stuck in the lungs and cause damage. This can then lead to respiratory problems - they're also bad for the environment - particulates and the clouds they help to produce reflect sunlight back into space. This means that less light reaches the earth, causing global dimming

Question 38

what problems are caused by carbon monoxide being released?

Answer 38

- carbon monoxide is really dangerous because it can stop your blood from doing its proper job of carrying oxygen around the body - it does this by binding to the haemoglobin in your blood that normally carries O2 - so less oxygen is able to be transported round your body - a lack of oxygen in the blood can lead to fainting, a coma or even death - carbon monoxide doesn't have any colour or smell, so it's very hard to detect. This makes it even more dangerous

Question 39

when is sulfur dioxide (SO2) released?

Answer 39

during the combustion of fossil fuels, such as coal, that contain sulfur impurities - the sulfur in the fuel becomes oxidised

Question 40

how are nitrogen oxides created?

Answer 40

from a reaction between the nitrogen and oxygen in the air, cause by the heat of the burning (this can happen in the internal combustion engines of cars)

Question 41

what happens when sulfur dioxide and nitrogen oxides mix with clouds?

Answer 41

they form dilute sulfuric acid or dilute nitric acid. This then falls as acid rain

Question 42

what effects does acid rain have?

Answer 42

it kills plants and damages buildings and statues. It also makes metal corrode.

Question 43

how can sulfur dioxide and nitrogen oxides be bad for human health?

Answer 43

they cause respiratory problems if they're breathed in

Question 44

how can you test for sulfur impurities in a fuel?

Answer 44

you bubble the gases from combustion through a solution containing universal indicator - if the fuel contains sulfur, the gases will contain SO2 which will form sulfuric acid and turn the Universal indicator red