Topic 9: Chemistry of the Atmosphere

• What is acid rain?

  Rain that is acidic due to dissolved gases
• What causes acid rain?

  Dissolved gases from burning fossil fuels
• What is a carbon footprint?

  Total greenhouse gases emitted by a product
• What does the term environmental implication refer to?

  The effect that an activity has on the environment
• What are fossil fuels?

  Natural fuels formed from living organisms
• What is global climate change?

  A long-term shift in global climate patterns
• What is global dimming?

  A reduction in light reaching the Earth's surface
• What causes global dimming?

  Carbon particulates can cause global dimming
• What is the greenhouse effect?

  Increase in Earth's temperature due to gases
• What are greenhouse gases?

  Gases that trap infra-red radiation in the atmosphere
• Name three greenhouse gases.

  Water vapour, carbon dioxide, methane
• Why are greenhouse gases important for life on Earth?

  They maintain temperatures high enough to support life
• What are particulates?

  Small particles that cause global dimming
• How do carbon particulates affect health?

  They cause health problems for humans
• What is produced by photosynthesis?

  Oxygen and glucose
• How did photosynthesis affect the early atmosphere?

  It decreased carbon dioxide levels
• What is the equation for photosynthesis?

  6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
• What are pollutants?

  Substances with undesired effects on the environment
• What are the key concepts in the chemistry of the atmosphere?

  • Acid rain
  • Carbon footprint
  • Environmental implication
  • Fossil fuels
  • Global climate change
  • Global dimming
  • Greenhouse effect
  • Greenhouse gases
  • Particulates
  • Photosynthesis
  • Pollutants
• What are the main gases in the atmosphere today?

  ~80% nitrogen and ~20% oxygen
• What does ∼ mean in the context of gas proportions?

  It means around or approximately
• How long have the proportions of gases in the atmosphere remained stable?

  For 200 million years
• Why is evidence about the Earth's early atmosphere limited?

  Due to the long time scale of 4.6 billion years
• What was one theory about the early atmosphere of Earth?

  Intense volcanic activity released gases
• What gases may have been present in the early atmosphere?

  Mainly CO2 with little or no O2
• What gases did volcanoes produce that contributed to the atmosphere?

  Nitrogen (N2), methane (CH4), and ammonia (NH3)
• What happened to water vapor in the early atmosphere?

  It condensed to form the oceans
• How did CO2 levels change due to the formation of oceans?

  CO2 dissolved in water, reducing atmospheric CO2
• What is the only theory of the early atmosphere that needs to be known?

  The theory of volcanic activity releasing gases
• How did algae and plants contribute to the oxygen in the atmosphere?

  They produced O2 through photosynthesis
• What is the photosynthesis equation for producing glucose and oxygen?

  6CO2 + 6H2O -> C6H12O6 + 6O2
• When did algae first produce oxygen?

  About 2.7 billion years ago
• How did the percentage of oxygen change over the next billion years?

  It gradually increased to support animal evolution
• How did algae and plants decrease the percentage of CO2 in the atmosphere?

  By photosynthesis, converting CO2 to O2
• What geological processes contributed to the decrease of CO2?

  Formation of sedimentary rocks and fossil fuels
• What types of sedimentary rocks contain carbon?

  Limestone and coal
• How are fossil fuels produced?

  From the remains of decayed plants and animals
• What role did decayed plants and animals play in CO2 levels?

  They contributed to the formation of fossil fuels
• What do greenhouse gases maintain on Earth?

  Temperatures high enough to support life
• Which gases are considered greenhouse gases?

  Water vapour, CO₂, and CH₄