T9 chemistry of the atmosphere

Question 1

describe the properties of gases in the modern atmosphere

Answer 1

around 80% of N2
20% of O2
small quantities of CO2, H2O and noble gases

Question 2

describe Earth’s early atmosphere and how it was formed

Answer 2

1. earth was hot when it was formed
2. there was significant volcanic activity
3. gases have been released from these volcanoes
4. these gases included CO2, N2, CH4, NH3, H2O

Question 3

how did the amount of oxygen in the atmosphere increase

Answer 3

algae and plants produced the atmospheric O2 by photosynthesis which can be represented by the equation:
6CO2 + 6H2O > C6H12O6 + 6O2

as the amount of O2 gradually increased, there were more plants that produced more oxygen

Question 4

how did the amount of carbon dioxide in the atmosphere decrease

Answer 4

a. some was dissolved in the oceans, where it reacted with metal ions to form insoluble carbonates such as CaCo2 or was taken in by animals to become a part of skeleton. When an animal dies, it becomes a sedimentary rock
b. some CO2 was used in photosynthesis to make oxygen

Question 5

what is the greenhouse effect

what are greenhouse gases

Answer 5

maintain temperatures on Earth high enough to support life

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

water vapour, carbon dioxide, and methane

Question 6

why is the greenhouse effect necessary for life

Answer 6

natural phenomenon

without it, 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

• sea level rise, floodings and increased coastal erosion
• more frequent and severe storms
• changes in amount and distribution of rainfall
• temperature increase and water stress
• change in distribution of wildlife species
• coral bleaching

Question 9

what is a carbon footprint

Answer 9

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 energy supplies
• energy conservation
• carbon capture and storage where CO2 is trapped in solvents and stored underground
• carbon taxes and licences
• carbon neutrality - zero net release
• carbon off-setting including through tree planting

Question 11

what are the problems of reducing the carbon footprint

Answer 11

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

Question 12

advantages of complete combustion

Answer 12

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

Question 13

how is pollution caused by combustion

Answer 13

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 14

issues regarding sulfur dioxide and oxides of nitrogen

Answer 14

sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain (damages plants and buildings)

Question 15

what problems do particulates cause

Answer 15

cause global dimming by reducing the amount of sunlight that reaches the Earth’s surface

particulates cause health problems due to damage to the lungs