C9 - Chemistry of the Atmosphere

• What approximate percentage of the modern atmosphere is composed of N2?

  Around 80%
• What approximate percentage of the modern atmosphere is composed of O2?

  20%
• Besides nitrogen and oxygen, what other gases are present in small quantities in the modern atmosphere?

  CO2, H2O, and noble gases
• What was the Earth like when it was first formed?

  Hot
• What geological activity was significant on the early Earth?

  Volcanic activity
• How were the gases in the Earth’s early atmosphere released?

  From volcanoes
• Which gases were present in the Earth's early atmosphere?

  CO2, N2, CH4, NH3, H2O
• How did algae and plants increase the amount of oxygen in the atmosphere?

  By photosynthesis
• What is the equation that represents photosynthesis?

  6CO2 + 6H2O → C6H12O6 + 6O2
• As the amount of oxygen in the atmosphere increased, what happened to the plant population?

  There were more plants
• How was CO2 removed from the early atmosphere by the oceans?

  It dissolved and reacted with metal ions
• What compound did carbon dioxide react with to form insoluble carbonates in the oceans?

  Metal ions
• What happens to the skeletons of animals that used CO2 to form them after the animals die?

  They become sedimentary rock
• Besides dissolving in oceans, what other process used CO2 to decrease its amount in the atmosphere?

  Photosynthesis
• What is the role of greenhouse gases in the atmosphere?

  Maintain temperatures high enough to support life
• How do greenhouse gases affect radiation from the sun and Earth?

  Allow short wavelength radiation, absorb long wavelength
• What are the greenhouse gases?

  Water vapour, carbon dioxide, methane
• Why is the greenhouse effect necessary for life on Earth?

  Without it, Earth would be too cold
• Which human activities have led to an increase in carbon dioxide in the atmosphere?

  Combustion and deforestation
• Which human activities have led to an increase in methane in the atmosphere?

  Increased farming and decomposition in landfills
• What are the potential effects of global climate change?

  • Sea level rise, causing flooding and coastal erosion
  • More frequent and severe storms
  • Changes in rainfall amount, timing, and distribution
  • Temperature and water stress for humans and wildlife
  • Changes in food-producing capacity of some regions
  • Changes to the distribution of wildlife species
• What does the term "carbon footprint" describe?

  Total greenhouse gases emitted over a life cycle
• What actions can be taken to reduce a carbon footprint?

  • Increased use of alternative energy supplies
  • Energy conservation
  • Carbon capture and storage
  • Carbon taxes and licences
  • Carbon offsetting, including tree planting
  • Carbon neutrality – zero net release
• What are the challenges of reducing the carbon footprint?

  • Scientific disagreement over causes and consequences
  • Lack of public information and education
  • Lifestyle changes that people resist
  • Economic considerations
  • Incomplete international cooperation
• What are the advantages of complete combustion?

  • Less soot (carbon particulates) is made
  • More heat per gram of fuel is released
  • Poisonous carbon monoxide is not produced
• How is pollution caused by combustion?

  • Gases released: carbon dioxide, water (vapour), carbon monoxide, sulfur dioxide, and nitrogen oxides
  • Solid particles and unburned hydrocarbons may also be released
• What are the environmental and health issues related to sulfur dioxide and oxides of nitrogen?

  Respiratory problems and acid rain
• What damage does acid rain cause?

  Damages plants and buildings
• How do particulates, such as carbon particles, affect the Earth's climate?

  Cause global dimming
• What are the health problems caused by particulates?

  Damage to the lungs