chemistry of the atmosphere

• What is the main gas in the Earth's atmosphere?

  Nitrogen
• What percentage of the atmosphere is nitrogen?

  80%
• What percentage of the atmosphere is oxygen?

  20%
• What are some other gases present in the atmosphere?

  CO2, H2O(g), noble gases
• Why is evidence of the early atmosphere limited?

  Due to the time scale of 4.6 billion years
• What does one theory suggest about the early atmosphere?

  It was formed by volcanic activity releasing gases
• What gases may have been present in the early atmosphere?

  CO2, N2, CH4, NH3
• What happened to water vapor in the early atmosphere?

  It condensed to form the oceans
• How did CO2 levels decrease in the atmosphere?

  Through dissolution in water and sediment formation
• What is the equation for photosynthesis?

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

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

  It gradually increased to support animal evolution
• How did algae and plants affect CO2 levels?

  They decreased CO2 through photosynthesis
• What contributed to the formation of sedimentary rocks?

  Decayed remains of plants and animals
• How are fossil fuels formed?

  From the remains of decayed plants and animals
• What is the relationship between photosynthesis and atmospheric oxygen levels?

  Photosynthesis increases oxygen levels in the atmosphere
• What do greenhouse gases maintain on Earth?

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

  Water vapour, CO₂, and CH₄
• What is the greenhouse gas effect?

  • Electromagnetic radiation from the sun passes through the atmosphere
  • Earth absorbs some radiation and warms up
  • Some heat is radiated as infrared radiation
  • Greenhouse gases absorb some IR radiation
  • Atmosphere warms up, leading to the greenhouse effect and global warming
• What human activities increase greenhouse gases?

  Driving, consuming electricity, raising livestock
• What is a major belief among scientists regarding human activities and climate change?

  They believe it will increase Earth's surface temperature
• Why is modeling global climate change difficult?

  Because it involves complex systems
• What are some potential effects of global climate change?

  Extinction of species, rising sea levels, migration
• What is the carbon footprint?

  Total amount of CO₂ and greenhouse gases emitted
• How can the carbon footprint be reduced?

  By reducing emissions of CO₂ and CH₄
• What are some methods to reduce carbon emissions?

  Using less electricity, reducing travel, planting trees
• What limitations exist in reducing carbon emissions?

  It can be difficult, expensive, and land-use competing
• What is a major source of atmospheric pollutants?

  Combustion of fuels
• What do most fuels contain?

  Carbon and/or hydrogen, and some sulfur
• What gases are released when a fuel burns?

  Carbon dioxide, water, carbon monoxide, nitrogen oxides
• What forms particulates in the atmosphere?

  Solid particles and unburned hydrocarbons
• What happens during incomplete combustion?

  Solid soot, carbon monoxide, and unburnt fuel are released
• What is produced when hydrocarbons combust?

  Carbon dioxide and water
• What is carbon monoxide?

  A toxic, colorless, and odorless gas
• What do sulfur dioxide and nitrogen oxides cause?

  Acid rain and respiratory problems
• What are the effects of particulates in the atmosphere?

  Global dimming and human health problems
• What are the main atmospheric pollutants from fuel combustion?

  • Carbon dioxide
  • Water vapor
  • Carbon monoxide
  • Oxides of nitrogen
  • Solid particles
  • Unburned hydrocarbons
• What are the properties and effects of key atmospheric pollutants?

  • Carbon monoxide: toxic, colorless, odorless
  • Sulfur dioxide and nitrogen oxides: cause acid rain and respiratory issues
  • Particulates: cause global dimming and health problems
• What is acid rain?

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

  Dissolved gases from burning fossil fuels