Chemistry of the Atmosphere

Question 1

Describe phase 1 of the formation of the earth’s early atmosphere.

Answer 1

-earth’s surface covered in volcanoes that erupted and released gases.
-probably mostly carbon dioxide, virtually no oxygen
-also released nitrogen and water vapour
-small amounts of methane and ammonia

Question 2

Describe phase 2 of the formation of the earth’s early atmosphere.

Answer 2

-water vapour condensed to form oceans
-carbon dioxide removed from atmosphere as its dissolved in oceans
-carbonate precipitates formed sediments on the seabed
-green plants and algae evolved and absorbed some CO2 for photosynthesis
-marine animals evolve with carbonates in shells and skeletons
-organisms die, are covered in sediment and some of the carbons are locked up in rocks and fossil fuels

Question 3

Describe phase 3 of the formation of the earth’s early atmosphere.

Answer 3

-plants and algae produce oxygen using photosynthesis
-as oxygen built up more complex life, like animals, could grow

Question 4

What is the approximate composition of the atmosphere today?

Answer 4

80% nitrogen
20% oxygen
1% carbon dioxide, noble gases, water vapour etc.

Question 5

How do greenhouse gases insulate the earth’s atmosphere? (The greenhouse effect)

Answer 5

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 (thermal) radiation that is reflected back off the surface of the earth.

Question 6

What are some of the forms of human activity that affect the amount of greenhouse gases in the atmosphere?

Answer 6

• Deforestation - fewer trees means less CO2 is removed from the atmosphere
• Burning fossil fuels - carbon that was locked up is released as CO2
• Agriculture - more farm animals produce more methane during digestive processes
• Creating waste - more landfill sites and waste from agriculture mean more CO2 and methane released from waste decomposition

Question 7

What are the scientific beliefs about carbon dioxide being linked to climate change and what are the issues with proving this.

Answer 7

• scientists believe that increasing CO2 levels have contributed to climate change
• the evidence has been peer-viewed
• but the earth’s climate is so complex that its hard to make a model that isn’t oversimplified
• this has led to speculation that stories may be biased or omit information

Question 8

What are the possible consequences of climate change?

Answer 8

• polar ice caps melting leading to a rise in sea levels and flooding in coastal areas
• changes in rainfall patterns causing floods or droughts, could lead to famine
• more intense storms
• changes in temperature and rainfall may affect wildlife

Question 9

What is a carbon footprint?

Answer 9

The measure of the amount of carbon dioxide and other greenhouse gases released over the full life cycle of something. E.g. a product, service or event.

Question 10

Why is it so hard to measure something’s carbon footprint?

Answer 10

Because there are so many factors to consider (e.g. the emissions from sourcing the parts used to make a product, transporting it, using it, disposing of it etc). But a rough calculation can still give an idea of what the worst emitters are.

Question 11

What are some of the ways that carbon footprints can be reduced?

Answer 11

• using renewable energy sources or nuclear energy instead of fossil fuels
• using more efficient processes to conserve energy and reduce waste (which decomposes to release methane)
• taxing companies or individuals based on how much they emit
• capping the emissions of greenhouse gases that companies produce and then selling licenses up to that cap
• technology that captures the CO2 produced by burning fossil fuels before they’re released so they can be stored deep underground

Question 12

What are some of the difficulties with methods for reducing CO2 emissions?

Answer 12

• requires a lot of work
• could impact the economic growth of communities
• its hard to make international agreements because not everyone is onboard
• most countries don’t want to sacrifice their economic growth if they don’t think others will too
• it’s hard to get people to change their lifestyle if they aren’t educated enough about the importance of it

Question 13

Describe the combustion of fossil fuels.

Answer 13

-they contain hydrocarbons which are oxidised during combustion to release CO2 and water vapour
- when there’s a lot of oxygen all the fuel burns (complete combustion)
- if there’s not enough some of it doesn’t burn (incomplete combustion) and soot and unburned fuel are released and carbon monoxide and dioxide are produced

Question 14

What are the problems caused by particulates in the air produced by incomplete combustion?

Answer 14

• can get stuck in the lungs, causing damage
• reflect sunlight back into space meaning less light can reach the earth (global dimming)

Question 15

What are the dangers of the carbon monoxide that’s released by incomplete combustion?

Answer 15

• can stop blood from properly transporting oxygen by binding to the haemoglobin that carries it
• lack of oxygen in blood can lead to fainting, coma, death etc
• no colour or smell so its hard to detect

Question 16

How are sulfur dioxide and nitrogen oxides produced?

Answer 16

• sulfur dioxide is from the combustion of fossil fuels which contain sulfur impurities
• nitrogen oxides are from a reaction between nitrogen and oxygen in the air, caused by the heat from burning things

Question 17

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

Answer 17

They form dilute sulfuric acid or dilute nitric acid which then falls as acid rain. This kills plants, damages buildings, corrodes metal etc. The two gases can also cause issues if breathed in.