Gases in Atmosphere

• What is the main focus of the chapter on gases in the atmosphere?

  The chapter concentrates on oxygen and carbon dioxide.
• Why is carbon dioxide significant in the context of climate change?

  Carbon dioxide is a greenhouse gas that may contribute to climate change.
• What are the learning objectives of the chapter on gases in the atmosphere?

  • Know the approximate percentages of the four most abundant gases in dry air.
  • Understand how to determine the percentage of oxygen in air using experiments.
  • Describe the combustion of elements in oxygen.
  • Describe the formation of carbon dioxide from metal carbonates.
  • Know that carbon dioxide is a greenhouse gas contributing to climate change.
• What are the approximate percentages by volume of nitrogen and oxygen in dry air?

  Nitrogen is approximately 78.1% and oxygen is approximately 21.0%.
• What does the percentage of carbon dioxide in the air indicate?

  The percentage of carbon dioxide is very small but is rising steadily due to human activity.
• What are the approximate percentages of the four most abundant gases in unpolluted, dry air?

  • Nitrogen: 78.1%
  • Oxygen: 21.0%
  • Argon: 0.9%
  • Carbon Dioxide: 0.04%
• What is the approximate fraction of oxygen in the air?

  The approximate fraction of oxygen in the air is about 1/5.
• What is the basic principle behind measuring the percentage of oxygen in the air?

  The principle involves reacting something with oxygen and measuring the volume decrease.
• What methods can be used to measure the percentage of oxygen in the air?

  • Reacting metals (e.g., iron) with air.
  • Reacting non-metals (e.g., phosphorus) with air.
  • Observing volume decrease as oxygen is consumed.