C9-Evolution of the Earth's atmosphere

Question 1

1) How old is the Earth supposed to be?
2) What does one theory suggest what happened in the first billion years?
3) How is the Earth’s early atmosphere recorded to be?
4) Why is the evidence for early atmosphere limited?

Answer 1

1) It is recorded to be 4.6 billion years old which means that scientists cannot be certain about the early atmosphere.
2) One theory suggests that during the first billion years of the Earth’s existence there was an intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form the oceans.
3) At the start of this period, the Earth’s atmosphere may have been like the atmospheres of Mars and Venus today, consisting of mainly carbon dioxide with little or no oxygen gas
4) Evidence for the early atmosphere is limited because of the time scale of 4.6 billion years.

Question 2

Alongside, C02, what other gases did volcanic activity release? Why did nitrogen built up?

Answer 2

Volcanic activity also released nitrogen which builds up in the atmosphere over time as it is inert and not reactive, as well as water vapour and small amounts of methane and ammonia.

Question 3

What % of the gases are in the Earth’s atmosphere today? (3)

Answer 3

In the Earth’s atmosphere, there is:

• approximately 80% nitrogen which is 4/5 of the Earth’s atmosphere and there is
• 1/5 which is approx 20% oxygen
• small proportions of various other gases including Co2, water & noble gases such as argon.

Question 4

1) What happened as the Earth cooled?

2) What can the Earth’s atmosphere than be compared to today?

Answer 4

As the Earth cooled, water vapour condensed to form the oceans.

2) The Earth’s atmosphere then was very much like the atmosphere of Venus and Mars today.

Question 5

Give reasons as to why the % of carbon dioxide has been reduced from the original value? (3)

Answer 5

1) Lots of C02 was removed from the early atmosphere as it dissolved in the oceans to form weak acids and went through many different reactions to form carbonate precipitates that formed sediments on seabeds.
2) Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis and as the plants produced more oxygen, it allowed marine animals to evolve and their shells and skeletons contained carbonates from the oceans
3) Carbon dioxide was also decreased by the formation of sedimentary rocks and fossil fuels that locked up carbon after the organism died- CCS- Carbon Capture &Storage.

Question 6

Give reasons as to why the % of oxygen has been increased from the original value? ( give within a time frame)

Answer 6

1) Around 2.7 billion years ago, photosynthetic algae first evolved in the oceans and they were able to photosynthesis and release oxygen as a waste product.
Over the next billion years, plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve.

Question 7

Describe the process as to how the carbon is ‘locked up’ in rock?

What is produced through this process?

Answer 7

1) When plants, planktons and marine animals die, they fall to the seabed and get buried by layers of sediment and over millions of years, they become compressed under the pressure and form sedimentary rocks, oil and gas- trapping the carbon within them and helping keep CO2 levels in the atmosphere reduced.
2) Through this process, fossil fuels are produced like coal, crude oil and natural gas.

Question 8

What is crude oil, natural gas and coal formed by?

What is limestone made up of?

Answer 8

Crude oil and natural gas are formed from deposits of plankton and these fossil fuels form reservoirs under the seabed when they get trapped in rocks.

Coal is a sedimentary rock made from thick plant deposits.

Limestone is mainly made up calcium carbonate deposits from the shells and skeletons of marine organisms.

Question 9

Why did methane and ammonia levels decrease?

Answer 9

Methane reacted with oxygen in the atmosphere which formed Co2+ H20 and they reacted with the oxygen formed by evolving algae and plants.

Ammonia reacted with Oxygen to form nitrogen and water and these reactions removed methane and ammonia from the atmosphere

Question 10

Why are scientists not sure about the early atmosphere? *

2

Answer 10

1) Occurred 4.6 billion years ago.

2) Limited or no evidence proof.

Question 11

What are the 3 key Greenhouse gases and list the other 2 as well?

List why GG are good?

Answer 11

• Co2
• Water vapour
• Methane
• Ozone
• Nitrous Oxide.

-GG in the atmosphere are needed to maintain temps on Earth that are warm enough to support life.

Question 12

Describe the process of the greenhouse effect? (3)

Answer 12

1) GG allow short wl such as UV to pass through the atmosphere; it is then absorbed by the Earth but not by the greenhouse gases.
2) To cool down, the Earth remits longer wl, like Infra-Red Radiation, which is absorbed by the layer of greenhouse gas. The longwave radiation is thermal radiation, therefore, it results in warming the surface of the Earth.
3) Such radiation causes bonds in the molecules of the greenhouse gases to vibrate, causing the temperature to rise.

The higher the proportion of greenhouse gases in the air, the more energy is absorbed.

Question 13

What are some forms of human activity that affects the amount of greenhouse gases in the atmosphere? (4)

What happens as the temp rises in regards to the oceans?

Answer 13

1) Deforestation; fewer trees means less Co2 is removed from the atmosphere via photosynthesis.
2) Burning fossil fuels- carbon that was ‘locked up’ in these fuels is released as CO2.
3) Agriculture; more farm animals produce more methane through digestive processes
4) Creating waste: more landfill sites and more waste from agriculture means more Co2 and methane released by the decomposition of waste.

Also as the temp rises, the CO2 gets less and less soluble in water which means the oceans less effective as the ‘CO2 sinks’

Question 14

How can the levels of greenhouse gases in the atmosphere be monitored?

Answer 14

-Using an instrumental technique called infrared spectroscopy as infrared stimulates the bonds in Co2 and methane to vibrate more vigorously, absorbing some of the radiation, which can be detected and displayed on the infrared spectrum

Question 15

How is Co2 linked to climate change?

Is the information reliable?

Answer 15

• the average temp of the Earth’s surface has been increasing and most scientists agree that extra CO2 from human activity is causing this increase and will lead to climate change.
• evidence for this has been peer-reviewed so the info can be seen reliable but stories can be biased in the media or only some of the info is given.

Question 16

Why is it difficult to fully understand the Earth’s climate? (2)

Answer 16

1) difficult to predict the effects of climate on rising levels of greenhouse gases on a global scale.
2) Earth’s climate is very complex and there are so many variables, that it’s very hard to make a model that isn’t oversimplified

Question 17

What is a major cause for climate change?

Answer 17

An increase in average global temperature is a major cause of climate change.

Question 18

Give 2 reasons why more evidence is needed to support any conclusions made by the scientific group? (3)

Answer 18

1) Lack of peer review.
2) Using simplified models.
3) Bias- paid by the government.

Question 19

What are the 4 effects of global climate change?

Answer 19

1) Polar Ice caps meltings- leading to coastal erosion as the levels of water are increasing, resulting in flooding.
2) Increase in extreme weather conditions- the frequency and severity of storms may also increase.
3) Change in rainfall patterns ( the amount, timing and distribution) may cause some regions to have too little or too much water. This along, with changes in temps, may affect the ability of certain regions to produce food and affect agriculture.
4) Changes in temp and the amount of water available- in habitat may affect wild species, leading to differences in their distributions.

Question 20

What is carbon footprint a measure of?

Answer 20

• Carbon footprint is a measure of the amount of Co2 and other greenhouse gases released over the full life cycle over a product or service.

Question 21

What are some ways to reduce carbon footprint? (5)

Answer 21

Reduce carbon footprint:

• Using renewable energy sources or nuclear energy could be used instead of fossil fuels.
• Using more efficient processes could conserve energy and cut waste as lost of waste decomposes to release methane, so this will reduce methane emissions.
• Gov could tax companies or individuals based on the number of greenhouse gases they emit
• Gov put a cap on emissions of all gg that companies make- then sell licenses for emissions up to that cap.
• Technology can capture the Co2 by burning fossil fuels before it’s realised in the atmosphere- it can be stored deep underground in cracks in the rock such as oil wells.

Question 22

Why is it difficult for reductions to be made? (4)

Answer 22

• lots of work need to be done on alternative technologies that will result in lower Co2 emissions.
• these changes could impact on the ecnomic growth for communities which could be importsnt for countries that are still developing.
• hard to make international agreements- countries may not want to sacrifice their economic development.
• individuals in developed countries need to make changes in their lifestyles and it may be hard to get them to do so if they don’t want to and there isn’t enough education provided about why the changes are necessary and how to make them.

Question 23

What happens during incomplete combustion and what is produced?

Answer 23

Fossil fuels, such as crude oil and carbon, contain hydrocarbons and when there’s not enough oxyfen, some of the fuel doesn’t burn and in these conditions, releases solid particules ( called particulates) of soot( carbon) and unburnt fuel are relesed and carbon monoxide can be produced as well as carbon dioxide.

Question 24

What are solid particulates?

List some problems particulates in the air can cause? (2)

Answer 24

Solid particles and unburned hydrocarbons may also be released that form particulates in the atmospher

1) Particulate are inhaled- they can get stuck in the lungs and cause damage- lead to respiratory problems( also asthma)
2) Bad for the environment and reflect sunlight into space meaning less light reaches the Earth causing global dimming.

Question 25

List some problems carbon monoxide in the air can cause? (2)

Answer 25

• bind to the haemoglobin in blood- less oxygen is transported around the body- a lack of oxygen can lead to fainting, coma, or even death.
• carbon monoxide doesn’t have any colour or smell so it’s v hard to detect- making it more dangerous.

Question 26

what 2 other gases are released during combustion (2)

what happens when these gases mix with the clouds?

Answer 26

1) sulfur dioxide is released during the combustion of fossil fuels that contain sulfur impurities and the sulfur in the fuel becomes oxidised.
1) nitrogen oxides are created from a reaction between the nitrogen and oxygen in the air, caused by the heat of the burning and this can happen in the internal combustion engine of cars.

when these gases mix with clouds, they form dilute sulfuric acid or dilute nitric acid and this falls as acid rain- which kills plants and damages buildings and statues- it also makes metal corrode.
- they can also cause respiratory problems.

Question 27

So2 gas also reacts with water? how can sulfur impurities be tested?

Answer 27

• reacts with water to form sulfuric acid and you cann test for sulfur inpurities in a fuel by bubbling the gases from combustion through a solution containing a universal indicator- if the fuel contains sulfur, the gases will contain Sio2 which will form sulfuric acid and turn the UI red.

Question 28

what are the key effects of acid rain?(4)

Answer 28

1) kill plant and vegetation.
2) accumulates in stagnant waters eg lakes.
3) damages trees and metal structures/ statues,
4) damages buildings with limestone

Question 29

list the balanced equations of sulphur reacting with oxygen, water in the clouds and the gas reacting with oxygen?

Answer 29

1) S(s) + O2-> SO2(g)
2) SO2 (g) + H20 (l) -> H2SO3 (aq)
3) 2H2SO3 + O2 -> 2H2SO4

Question 30

list the balanced equations of nitrogen reacting with oxygen, water in the clouds and the gas reacting with oxygen?

Answer 30

1) N(s) + O2-> NO2(g)
2) 2NO2 (g) + H20 (l) -> HNO3+ HNO2(aq)
3) 2HNO2 + O2 -> 2HNO3

Question 31

what’re the formulae for sulphurous gas?
nitrous gas?

-sulphuric acid and nitric acid?

Answer 31

sulphurous gas- 2H2SO3
nitrous gas- 2HNO2

• sulphuric- 2H2SO4
• nitric- 2HNO3

Question 32

What colour is sulphur and what does it burn with?

Answer 32

It is naturally found in labs as a yellow solid and it burns with a bright blue flame to produce an acidic group.

Question 33

Outline how sedimentary rocks are formed? (1 mark)

Answer 33

• matter that is compressed and buried over millions of years.

Question 34

An increase in global temp could cause sea levels to rise. Give two potential consequences of rising sea levels.

Answer 34

1) Flooding

2) costal erosion

Question 35

Suggest 2 disadvantages for companies of capturing and storing Co2?

Answer 35

• expensive and difficult to store the co2

- specialist equipment is required.

Question 36

Explain why may countries may be resistant to reduce carbon footprints? (2 marks)

Answer 36

1) Gov may be resistant on imposing changes if it will affect economic growth especially if other countries aren’t using the methods a nd there are international disagreements (1) or if a country is still developing.

Question 37

Why can combustion of coal produce sulfur dioxide?

Answer 37

Coal contains sulphur impurities.

Question 38

Explain how cars produce nitrogen oxides ( 2 marks)

Answer 38

Reaction of nitrogen and oxygen from air at high temps lead to nitrogen oxide