9. Chemistry of the atmosphere

Question 1

Describe the earth’s early atmosphere and how it was formed?

Answer 1

1. The earth was hot when it was formed
2. there was significant volcanic activity
3. gases have been released from these volcanoes
4. these gases include carbon dioxide, nitrogen, methane, ammonia and water vapour

Question 1

Describe the proportions of gases in the modern atmosphere

Answer 1

• around 80% nitrogen
• around 20% oxygen
• small quantities of carbon dioxide, water vapour and noble gases

Question 2

How did the amount of oxygen in the atmosphere increase?

Answer 2

• Algae and plants produced the atmospheric oxygen by photosynthesis
• as the amount of oxygen gradually increased, there were more plants that produced more oxygen

Question 3

How did the amount of carbon dioxide in the atmosphere decrease?

Answer 3

• when the oceans formed, carbon dioxide dissolved in the water and carbonates were precipitated producing sediment.
• some carbon dioxide was used in photosynthesis to make oxygen

Question 4

What are greenhouse gases, give some examples?

Answer 4

• they are gases in the atmosphere that maintain temperatures on earth high enough to support life
• eg. methane, water vapour, carbon dioxide

Question 5

What is the greenhouse effect?

Answer 5

• greenhouse gases allow short wavelength radiation from the sun to pass through the atmosphere to the earth’s surface,
• but absorb the outgoing long wavelength radiation from the earth, causing an increase in temperature

Question 6

Why is the greenhouse effect necessary for life?

Answer 6

it is a natural phenomenon. without it, the earth would be too cold for life to exist

Question 7

How have human activities led to an increase in greenhouse gases?

Answer 7

carbon dioxide - combustion and deforestation
methane - increased farming and decomposition in landfills

Question 8

What are the potential effects of global climate change?

Answer 8

1. Sea levels rise - which may cause flooding and increased coastal erosion
2. more frequent and severe storms
3. changes in the amount, timing and distribution of rainfall
4. temperature and water stress for humans and wildlife
5. changes in the food-producing capacity of some regions
6. changes to the distribution of wildlife species

Question 9

What is a carbon footprint?

Answer 9

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

Question 10

What actions can be taken to reduce a carbon footprint?

Answer 10

• increased use of alternative renewable energy supplies
• energy conservation
• carbon capture and storage
• carbon taxes and licenses
• carbon off-setting including through tree planting
• carbon neutrality - zero net release

Question 11

What is carbon capture and storage?

Answer 11

where carbon dioxide is trapped in solvents and stored underground

Question 12

What are the challenges faced with reducing a carbon footprint?

Answer 12

• scientific disagreement over causes and consequences of global climate change
• lack of public information and education
• lifestyle changes
• economic considerations
• incomplete international cooperation

Question 13

What are the advantages of complete combustion?

Answer 13

• less soot is made
• more heat per gram of fuel is released
• poisonous carbon monoxide is not produced

Question 14

What is soot?

Answer 14

carbon particles

Question 15

How is pollution caused by combustion?

Answer 15

• when a fuel burns, the gases released to the atmosphere include carbon dioxide, water vapour, carbon monoxide, sulphur dioxide and oxides of nitrogen
• solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere

Question 16

What are the issues regarding sulphur dioxide and oxides of nitrogen?

Answer 16

Sulphur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain. Acid rain damages plants and buildings

Question 17

What problems do particulates cause?

Answer 17

• Particulates, such as carbon particles, cause global dimming by reducing the amount of sunlight that reaches the earth’s surface.
• Particulates cause health problems for humans because of damage to the lungs