Chemistry of the atmosphere

Question 1

Describe the proportions of gases in the modern atmosphere

Answer 1

• 80% nitrogen
• 20% oxygen
• Small quantities of CO2, H2O and noble gases

Question 2

Describe earths early atmosphere and how it was formed

Answer 2

• Earth was hot when it formed
• There was significant volcanic activity
• Gases have been released from these volcanoes
• Including CO2, N2, H2O, NH3, CH4

Question 3

How did the amount of oxygen in the atmosphere increase?

Answer 3

• Algae and plants produced the atmospheric O2 by photosynthesis
• As the amount of O2 gradually increased, there were more plants that produced more oxygen

Question 4

How did the amount of CO2 in the atmosphere decrease?

Answer 4

• Some CO2 was dissolved in the oceans, where it reacted with metal ions to form insoluble carbonates, or taken in by animals to become a skeleton. Becoming sedimentary rock
• Some CO2 was used in photosynthesis to make oxygen

Question 5

What is the greenhouse effect

Answer 5

Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life
They allow short wavelength radiation from the sun to pass through the atmosphere to the Earth’s surface, but absorbs outgoing long wavelength radiation from earth causing an increase in temperature

Question 6

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

Answer 6

Carbon dioxide - Combustion and deforestation
Methane - Increased farming and decomposition in landfills

Question 7

Effects of climate change

Answer 7

• Sea level rise
• Changes in amount, timing and distribution of rainfall
• More frequent storms
• Droughts
• Changes in food producing capacity of regions
• Changes to distribution of wildlife

Question 8

What actions can reduce a carbon footprint

Answer 8

• Increased use of alternative energy supplies
• Energy conservation
• Carbon capture and storage
• Carbon taxes and licences
• Carbon off setting including through tree planting

Question 9

Advantages of complete combustion

Answer 9

• Less soot is made
• More heat per gram of fuel is released
• Poisonous carbon monoxide is not produced

Question 10

How is pollution caused by combustion

Answer 10

• Greenhouse gases are released into the atmosphere
• Solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere

Question 11

Issues with sulfur dioxide and oxides of nitrogen?

Answer 11

• Cause respiratory problems in humans
• Cause acid rain

Question 12

What problems do particulates cause?

Answer 12

Cause global dimming by reducing amount of sunlight that reaches the Earths surface.
Cause health problems because of damage to lungs