Topic 9 Chemistry of the Atmosphere

Question 1

1) Which gas makes up the largest proportion of Earth’s atmosphere?

Answer 1

1) Nitrogen is the most abundant gas in Earth’s atmosphere (about 80% of it, in fact).

Question 2

2) Many scientists believe Earth’s early atmosphere was abundant in carbon Give one theory about where this carbon dioxide might have come from.

Answer 2

2) Volcanic eruptions

Question 3

3) Why is there only limited evidence about Earth’s early atmosphere?

Answer 3

3) There is only limited evidence about Earth’s early atmosphere because it was so long ago a staggering 4.6 billion years, to be precise.

Question 4

4) Name two fossil fuels.

Answer 4

4) The three you should know are coal, crude oil and natural gas. Any two of these will do.

Question 5

5) Give a scientific theory for how the oceans formed.

Answer 5

5) The condensation of water vapour in the atmosphere.

Question 6

6) Name the process that plants and algae use to produce oxygen. What is the other product of this process?

Answer 6

6) Plants and algae use photosynthesis to produce oxygen and glucose.

Question 7

7) Suggest how the level of carbon dioxide in Earth’s early atmosphere might have initially been reduced.

Answer 7

7) Carbon dioxide may have dissolved in the oceans, forming sediments. Plants and algae may have also contributed by absorbing carbon dioxide during photosynthesis.

Question 8

8) Describe how limestone is formed.

Answer 8

8) Limestone is made from the shells and skeletons of marine organisms that fall to the seabed and become buried. Over time they become compressed, forming limestone.

Question 9

1) Why is the greenhouse effect essential for life on Earth?

Answer 9

1) The greenhouse effect keeps the planet warm enough to support life, by providing an insulating layer around the Earth.

Question 10

2) True or false? Greenhouse gases absorb long wavelength radiation.

Answer 10

2)

True. Greenhouse gases absorb long wavelength radiation, but don’t absorb short wavelength radiation.

Question 11

3) Give one human activity that increases the amount of methane in the atmosphere.

Answer 11

3) E.g. agriculture, use of landfill sites.

Question 12

4) How does the greenhouse effect work?

Answer 12

4) Greenhouse gases absorb the long wavelength radiation that is reflected off the Earth and re-radiate it in all directions, including back towards the Earth. This radiation is thermal
radiation, so it warms the surface of the planet.

Question 13

5) Explain why an increase in global temperatures could affect sea levels.

Answer 13

5) Increasing global temperatures could lead to the polar ice caps melting, which would cause sea levels to rise.

Question 14

6) Describe one other potential effect of global climate change.

Answer 14

6) E.g. changes in rainfall patterns could affect the production of food. The frequency and severity of storms may increase. Changes in temperature/amount of water available may affect the distribution of wild species. Rising sea levels could lead to flooding and costal erosion.

Question 15

7) Why is it difficult for scientists to fully understand the Earth’s climate?

Answer 15

7) Earth’s climate is complex and difficult to model, which makes it hard to fully understand.

Question 16

1) What does it mean if something has a large carbon footprint?

Answer 16

1) If something has a large carbon footprint, that means that it releases large amounts of greenhouse gases over its full life cycle.

Question 17

2) True or false? Reducing the amount of methane a product releases will reduce its carbon footprint.

Answer 17

2) True. Methane is a greenhouse gas, so if less of it is released by the product then the product will have a lower carbon footprint (so long as there isn’t a larger increase in other greenhouse gases given off as a result).

Question 18

3) Suggest an alternative energy source to fossil fuels, that has a lower carbon footprint.

Answer 18

3) E.g. nuclear energy or renewable energy sources like solar, wind and hydroelectric energy.

Question 19

4) Explain why it is difficult to measure carbon footprints.

Answer 19

4) There are a lot of factors to consider when measuring carbon footprints, like sourcing all the materials, manufacture, use and disposal. Therefore it gets quite complicated and difficult to measure. You can always do a rough calculation, though.

Question 20

5) Suggest one thing governments could do to try and reduce carbon emissions.

Answer 20

5) E.g. tax companies based on the amount of greenhouse gases they emit, or place a cap on the total emissions that companies can make, then sell licences for emissions up to the cap.

Question 21

6) Why are the actions of governments often limited?

Answer 21

6) Governments are often concerned that implementing changes will be bad for the country’s economy or make them unpopular. This can make it hard for them to reach decisions or international agreements. It can also be difficult for them to persuade individuals or businesses to change their behaviour.

Question 22

1) What are the products when a hydrocarbon burns in plenty of oxygen?

Answer 22

1) When a hydrocarbon burns in plenty of oxygen, complete combustion occurs and the only products are carbon dioxide and water.

Question 23

2) Why is carbon monoxide difficult to detect?

Answer 23

2) Carbon monoxide is colourless and odourless.

Question 24

3) How are nitrogen oxides produced?

Answer 24

3) Nitrogen oxides are formed when nitrogen and oxygen react together under high temperatures (such as in car engines).

Question 25

4) What are two negative effects of particulates in the atmosphere?

Answer 25

4) E.g. particulates reflect sunlight back into space. This means that less light reaches the Earth, causing global dimming. They can also cause respiratory problems if breathed in.

Question 26

5) How have human activities increased the level of sulfur dioxide in the atmosphere?

Answer 26

5) The burning of fossil fuels increases the level of sulfur dioxide in the atmosphere. This is because fossil fuels often contain sulfur impurities. When the fuels are burnt, the sulfur impurities are oxidised to sulfur dioxide, which is then released into the atmosphere.

Question 27

6) Describe how carbon monoxide affects the human body.

Answer 27

6) Carbon monoxide is a poison that prevents blood from taking up enough oxygen. Breathing it in can lead to fainting, a coma or, in the worst cases, death.

Question 28

7) How do nitrogen oxides result in damage to buildings?

Answer 28

7) Nitrogen oxides mix with clouds to form nitric acid. This then falls as acid rain, which corrodes metals and damages buildings.