Earth's Atmosphere and Human Activities

Earth's Atmosphere and Human Activities

• Human activities impact the environment due to technological advancements and population growth.
• CFCs (Chlorofluorocarbons) were widely used in aerosol propellants and refrigerants.
  • CFCs are not water-soluble and degrade slowly, contributing to ozone depletion.
  • CFCs absorb radiation in the 190-225 nm range, breaking the C—Cl bond and releasing chlorine atoms.
  • Chlorine atoms react with ozone, depleting its concentration in the atmosphere.
• Sulfur Dioxide (SO2) is a byproduct of burning coal and oil.
  • SO2 reacts with moisture in the air to form sulfuric acid, a major contributor to acid rain.
  • Acid rain corrodes building materials like marble and limestone by reacting with calcium carbonate.
  • Limestone is used to remove SO2 in flue gases.
• Carbon Monoxide (CO) is produced by incomplete combustion of carbon-containing materials.
  • CO binds to hemoglobin in red blood cells, preventing oxygen transport.
  • Exposure to high levels of CO can lead to loss of consciousness and death.
• Nitrogen Oxides (NOx) are primary components of smog, primarily emitted by vehicles.
• Photochemical smog forms when sunlight reacts with NOx, Volatile Organic Compounds (VOCs), and airborne particles.
• Greenhouse gases trap infrared radiation and contribute to global warming.
  • Water vapor, carbon dioxide, methane, nitrous oxide, HFCs, and CFCs are major greenhouse gases.
  • Increased CO2 levels are a major concern for global warming.
  • One liter of gasoline produces 2 kg of CO2.
• Methane (CH4) is produced in low-oxygen environments by anaerobic bacteria.
  • Methane is oxidized in the stratosphere, producing water vapor, a powerful greenhouse gas.
  • Natural gas extraction and transport can leak methane.

Earth's Water and Human Activities

• Water quality is crucial for life, but human activities can contaminate water sources.
• Dissolved oxygen (DO) is an indicator of water quality.
  • Cold-water fish require at least 5 ppm DO.
  • Organic materials degrade using DO in water by aerobic bacteria.
• Eutrophication occurs when excessive plant growth depletes DO in water bodies.
• Distillation is an energy-intensive process for removing salts from water, producing concentrated brine.
• Desalination is the removal of salts from seawater or brackish water.
  • Reverse osmosis forces water through a semipermeable membrane, concentrating pure water.
• Water purification involves filtration, aeration, and disinfection.
  • CaO and Al2(SO4)3 are used for particle removal.
  • Ozone or chlorine is used for disinfecting water.
• Water disinfection significantly reduced waterborne diseases.
• Chlorination of water produces trihalomethanes (THMs), potentially carcinogenic byproducts.

Earth's Soil and Human Activities

• Soil is a mixture of sand, silt, and clay.
• Green chemistry promotes environmentally friendly chemical products and processes.
• Green Chemistry Principles:
  • Prevention: Waste prevention is preferred over cleanup.
  • Atom Economy: Maximizing starting material conversion into the final product.
  • Less Hazardous Chemical Syntheses: Minimizing toxicity in synthesis.
  • Design of Safer Chemicals: Designing toxic-minimized chemicals with desired function.
  • Safer Solvents and Auxiliaries: Limiting use of toxic solvents.
  • Design for Energy Efficiency: Minimizing energy requirements of chemical processes.
  • Use of Renewable Feedstocks: Using renewable raw materials.
  • Reduction of Derivatives: Avoiding intermediate compound formation.
  • Catalysis: Using catalysts for increased yield and efficiency.
  • Design for Degradation: Creating products that degrade into harmless forms.
  • Real-Time Analysis for Pollution Prevention: Real-time monitoring to prevent hazardous substance formation.

Explore how human activities impact the Earth's atmosphere through the release of pollutants like CFCs, SO2, and CO. Learn about the chemical reactions and environmental consequences of these substances, including ozone depletion and acid rain. This quiz will deepen your understanding of the relationship between human actions and atmospheric changes.