Environmental Chemistry Chapter 23

Environmental Chemistry - Chapter 23

• Question 1: Select the Right Answer
  • Chromium (VI) use: (a)
  • Control growth of Fungus: (a)
  • Ozone layer's height in km: 25-28km
  • Components of environment: Atmosphere, hydrosphere, lithosphere, biosphere
  • CO₂: (c)
  • Acids: (b)
  • Chlorofluorocarbons: (c)

Environmental Components

• Components of Environment:
  • Atmosphere: Composed of gasses (N₂, CO₂, etc.).
  • Hydrosphere: All water bodies (oceans, rivers, etc.).
  • Lithosphere: Solid, rocky earth's crust.
  • Biosphere: Life-supporting areas on earth.

Atmosphere and Environmental Role

• Atmosphere: Surrounding gas layer around Earth, composed of N₂, O₂, CO₂, and other gasses.
• Atmospheric role:
  • Absorbs harmful radiation (cosmic rays, electromagnetic radiations from the sun).
  • Supports life through various gasses (N₂, O₂, etc.).
  • Important for photosynthesis (water vapor).

Air Pollution Sources

• Air pollutants:
  • Nitrogen oxides (NO, NO₂)
  • Volatile Organic Compounds (VOCs)
  • Carbon oxides (CO, CO₂)
  • Sulfur oxides (SO₂, SO₃)

Important Air Pollutants

• Important air pollutants:
  • Nitrogen oxides (NO, NO₂)
  • Volatile Organic Compounds (VOCs)
  • Peroxyacetyl Nitrates (PAN)
  • Carbon oxides (CO, CO₂)
  • Sulfur oxides (SO₂, SO₃)

Sources of CO Emission and Effects

• CO Emission Sources:
  • Incomplete combustion of fuels (agricultural, industrial).
  • Reactions in blast furnaces.
  • Cigarette smoke.
  • Incomplete combustion of carbon-containing compounds.
• CO Effects:
  • Anoxia (oxygen starvation) leading to suffocation.
  • Respiratory irritation.

Smog Types (Industrial vs. Photochemical)

• Smog: Combination of smoke and fog.
• Industrial Smog (Reducing Smog): Contains high amounts of SO₂, characterized by its reducing nature. Caused by burning coal.
• Photochemical Smog (Oxidizing Smog): Brownish/yellowish haze caused by high concentrations of oxidants (e.g., ozone). Often involves reactions from cars (exhaust emissions).

Global Warming

• Global Warming: Increase in Earth's average surface temperature due to increased greenhouse gasses.
• Predictions:
  • Increased greenhouse effect with substantial CO₂ increases.
  • Excessive CO₂ levels cause glaciers to melt, leading to floods in low-lying areas, changes in ocean biological activity, and shifts in agricultural patterns.

Gases Responsible for Greenhouse Effect

• Gases responsible for greenhouse effect:
  • CO₂
  • Water vapor
  • Methane
  • CFCs (Chlorofluorocarbons)
  • Nitrogen oxides

Volatile Organic Compounds (VOCs)

• Sources: Evaporation of solvents, incomplete combustion of fuels, naturally occurring compounds from trees (terpenes).
• Environmental effects: Eye irritation, respiratory irritation, some are carcinogenic, reduced visibility.

Peroxyacetyl Nitrates (PAN)

• Sources: Reaction of NO₂ with VOCs.
• Environmental effects: Eye irritation, high toxicity to plants, damages proteins, respiratory irritation.

Excess CO₂ Atmospheric Effects

• Excess CO₂ effects: Same as discussed under Global Warming predictions.

SO₂ as Pollutant: Sources and Effects

• Sources: Volcanic eruptions, burning oil and coal, roasting sulfides.
• Effects: Acid rain, respiratory irritation, loss of color in plants, fading of fabrics, damage to leather, paper, and paints.

Nitrogen Oxides (NOx)

• Sources: Combustion of fossil fuels (oil, coal, gas) in automobiles and industry.
• Effects: Decreased visibility due to yellowish color of nitrogen dioxide.

Ozone Layer - Safeguard

• Ozone (O₃): Protective layer in the stratosphere (15-25 km). Absorbs harmful UV rays from the sun, preventing damage to life.

Ozone Hole

• Ozone hole: Regions of reduced ozone concentration, primarily over Antarctica.
• Causes: Release of chemicals (CFCs, NOx) into the atmosphere which break down ozone. This allows UV rays through with damaging effects.

Ozone Layer Depletion Effects

• Depletion effects: Increased skin cancer rates in humans, damage to ecosystems, and reduced agricultural yields.

Water Pollution

• Water pollution: Contamination of water with substances that negatively affect human health, animal life, or ecosystems.
• Pollutants:
  • Oil spillage
  • Livestock waste
  • Industrial waste
  • Leather tanneries
• Effects: Unsuitable for drinking, recreation, agriculture, industry, and other forms of use.

Waste Water Treatment

• Wastewater treatment: Methods for removing pollutants from wastewater, including solids removal, oil & grease removal, soft organics removal, and hard organics removal, acids, and alkalis removal..

Acid Rain

• Acid rain: Rain with a pH lower than 5.6, caused by air pollutants such as sulfur dioxide (SO₂) and nitrogen oxides (NOx) reacting with water in the atmosphere.
• Explanation: SO₂, NO₂, and CO₂ react with water, producing acids like H₂SO₄, HNO₃, and H₂CO₃. These acids fall to Earth as rain or snow.

Acid Rain Impacts

• Impacts: Damage to plants (leaf drop), corrosion of buildings, metals, and other materials, acidification of lakes and rivers, harming aquatic life. Increased solubility of metals in water, which can harm living organisms.

Air Pollution Control Methods

• Control methods: Catalytic oxidation/converter in cars, modifying combustion techniques (e.g., reducing lead content in petrol), reducing emission of pollutants in industrial processes.

Thermal Pollution

• Thermal pollution: Increase in water temperature due to industrial activities.
• Sources: Cooling systems for power plants, industrial processes using water as a coolant.

Test your knowledge with this quiz on Environmental Chemistry Chapter 23, focusing on the components of the environment, the role of the atmosphere, and the implications of various gases. Examine key concepts such as ozone layer height and the importance of different gases in supporting life. Perfect for students looking to reinforce their understanding of environmental science.