Topic 9: Chemistry of the Atmosphere

Question 1

How much of the Earth’s atmosphere is made up from nitrogen?

Answer 1

80%

Question 2

How much of the Earth’s atmosphere is made up from oxygen?

Answer 2

20%

Question 3

What are some other gases present in the Earth’s atmopshere? [3]

Answer 3

1. Carbon dioxide
2. Water vapour
3. Noble gases

Question 4

Why is the evidence for the early atmosphere limited?

Answer 4

Due to the time scale of 4.6 billion years

Question 5

Describe the Earth’s early atmosphere
i) cause
ii) composition
iii) traces of?

Answer 5

i) Intense volcanic activity that released gases, forming the early atmosphere
ii) Atmosphere consisting mainly of carbon dioxide, little or no oxygen
iii) Traces of nitrogen, methane and ammonia

Question 6

How were oceans formed?

Answer 6

Water vapour condensed to form oceans

Question 7

What happened when the oceans were formed?

Answer 7

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

Question 8

Describe how the amount of oxygen in the atmosphere increased

Answer 8

Algae and plants produced the oxygen that is now in the atmosphere by photosynthesis (2.7 billion years ago)

Question 9

Describe how the amount of carbon dioxide in the atmosphere decreased

Answer 9

Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis

Question 10

Describe how deposits of coal, oil and gas (fossil fuels) were formed? [4]

Answer 10

1. When plants, plankton and marine animals die, they fall to the seabed
2. They get buried by layers of sediment
3. Over millions of years, they become compressed and form sedimentary rocks (coal), oil and gas
4. This traps the CO₂ within them

Question 11

What is limestone made from?

Answer 11

Sedimentary rock - however it is mostly calcium carbonate deposits from the shells and skeletons of marine organisms

Question 12

Describe the greenhouse effect and how it affects global temperature [4]

Answer 12

1. The sun gives out short wavelength radiation
2. This is reflected back by the Earth as thermal radiation
3. The thermal radiation is absorbed by greenhouse gases in the atmosphere
4. Greenhouse gases give out the thermal radiation in all directions including back towards Earth, causing the temperature to rise

Question 13

Examples of greenhouse gases [3]

Answer 13

1. Carbon dioxide
2. Water vapour
3. Methane

Question 14

Describe how human activities are resulting in more CO₂ in the atmosphere [2]

Answer 14

1. Deforestation means that there are less trees to remove CO₂ from the atmosphere via photosynthesis
2. When we burn fossil fuels, the carbon that was ‘locked up’ in these fuels get released as CO₂

Question 15

Describe how human activities are resulting in more methane in the atmosphere [2]

Answer 15

1. There are more farm animals e.g. cows which release methane through their digestion processes
2. More landfill sites and waste from agriculture means more methane released by decomposition of waste

Question 16

Why is evidence peer-reviewed?

Answer 16

To check that the information is reliable

Question 17

Why is it hard to fully understand the Earth’s climate? [2]

Answer 17

1. Complex
2. Too many variables to take into account

Question 18

Consequences of climate change [4]

Answer 18

1. Rising sea levels
2. Changes in rainfall patterns
3. Frequency and severity of storms
4. Species may become extinct or migrate

Question 19

Define ‘carbon footprint’

Answer 19

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

Question 20

Ways of reducing carbon footprint [3]

Answer 20

1. Switching to renewable energy sources
2. Using more efficient processes
3. Carbon capture

Question 21

State 2 things governments can do to try to reduce the greenhouse gas emissions of businesses

Answer 21

1. Tax companies on how many greenhouse gases emissions they create
2. Put a cap on the amount of greenhouse gas emissions companies can emit

Question 22

Why is it hard to reduce greenhouse gases emissions? [3]

Answer 22

1. Some renewables still in early development
2. Many economies still based off fossil fuels
3. Not everyone on board with plans to change

Question 23

How are particulates made?

Answer 23

Produced during incomplete combustion

Question 24

Problems with particulates [2]

Answer 24

1. Can get into people’s lungs and cause respiratory problems
2. Can cause global dimming

Question 25

How is carbon monoxide made?

Answer 25

Produced during incomplete combustion

Question 26

Problem with carbon monoxide

Answer 26

If breathed in, can starve our brain of oxgen and cause death

Question 27

Properties of carbon monoxide [2]

Answer 27

1. Colourless
2. Odourless

Question 28

How are is sulfur dioxide and nitrogen oxide made?

Answer 28

When impurities in hydrocarbons are oxidised when burnt

Question 29

Problems with sulfur dioxide and nitrogen oxide [2]

Answer 29

1. Can damage lungs and cause respiritory problems
2. Can cause acid rain