Chemistry: Air and Atmosphere

• Chemistry is the study of matter and its properties as well as how matter changes

Air and Atmosphere

• Air consists of a mixture of gases surrounding Earth
• The atmosphere is the layer of air above the Earth's surface
• Air is vital for the survival, facilitating animal respiration and plant photosynthesis
• The atmosphere shields Earth from harmful solar radiation and regulates temperature
• Air's primary components by volume include:
  • Nitrogen (N2): approximately 78%
  • Oxygen (O2): approximately 21%
  • Argon (Ar): about 0.9%
  • Carbon Dioxide (CO2): around 0.04%
  • Trace gases, such as neon, helium, and methane
• Air contains variable amounts of water vapor

Composition of Air

• Nitrogen is relatively inert, used by plants for protein creation
• Oxygen is crucial for both respiration and combustion processes
• Argon, a noble gas, finds use in lighting and various industrial applications
• Carbon dioxide is utilized by plants during photosynthesis; it also functions as a greenhouse gas, retaining heat
• Water vapor affects humidity levels and contributes to cloud formation
• Air also contains small amounts of other gases like neon, helium, methane, and ozone

Properties of Air

• Air has mass and occupies space
• Air has pressure, known as atmospheric pressure
• Air is compressible and expandable
• Air moves and creates wind, influenced by temperature and pressure differences

Importance of Air

• Air is vital for respiration, allowing animals to derive energy from their food
• Air provides carbon dioxide for photosynthesis, which plants use to produce food and oxygen
• Air regulates Earth's temperature, preventing extreme variations
• The ozone layer in the atmosphere protects living organisms from harmful ultraviolet radiation from the sun
• Air is used in various industrial processes, such as combustion and cooling

Air Pollution

• Air pollution involves the contamination of air through harmful substances like smoke, dust, and gases
• Common air pollutants are:
  • Particulate matter (PM)
  • Carbon monoxide (CO)
  • Sulfur dioxide (SO2)
  • Nitrogen oxides (NOx)
  • Ozone (O3)
  • Volatile organic compounds (VOCs)
• Air pollution sources:
  • Burning fossil fuels (coal, oil, and natural gas) in power plants, vehicles, and industries
  • Industrial processes
  • Agricultural activities, like fertilizer and pesticide use
  • Natural sources, including volcanic eruptions and dust storms
• Air pollution can cause harmful effects on human health:
  • Respiratory issues (asthma, bronchitis)
  • Cardiovascular diseases
  • Cancer
• Air pollution damages the environment by causing:
  • Acid rain
  • Smog
  • Depletion of the ozone layer
  • Global warming

Water

• Water (H2O) is composed of two hydrogen atoms and one oxygen atom
• Water is essential for all forms of life
• 71% of Earth's surface is water, mostly in oceans, seas, lakes, and rivers
• Water exists as a solid (ice), liquid (water), and gas (water vapor)
• Water is a universal solvent, capable of dissolving many substances

Sources of Water

• Surface water sources include rivers, lakes, and reservoirs
• Groundwater is stored underground in aquifers
• Rainwater originates from atmospheric precipitation

Properties of Water

• Pure water is colorless, odorless, and tasteless
• Water has a high specific heat capacity, enabling it to absorb much heat without significant temperature changes
• Water has high surface tension, which allows insects to walk on water
• Solid water (ice) is less dense than liquid water, allowing it to float
• Water is a polar molecule, giving it excellent solvent properties

Importance of Water

• Water is essential for all living organisms:
  • It is a major component of cells and body fluids
  • It is necessary for many biological processes, such as photosynthesis and digestion
  • It helps regulate body temperature
  • It transports nutrients and waste products
• Water is crucial for agriculture, industry, and domestic use

Water Pollution

• Water pollution is the contamination of water bodies by harmful substances such as chemicals, sewage, and pathogens
• Sources of water pollution:
  • Industrial discharge
  • Agricultural runoff
  • Sewage and wastewater
  • Oil spills
  • Mining activities
• Water pollution can cause harmful effects on human health and the environment:
  • Spread of waterborne diseases
  • Death of aquatic organisms
  • Contamination of drinking water sources
  • Damage to ecosystems

Water Cycle

• The water cycle (hydrologic cycle) describes continuous water movement on, above, and below Earth's surface:
  • Evaporation: liquid water turns into water vapor due to solar heat
  • Transpiration: release of water from plants into the atmosphere
  • Condensation: water vapor cools and turns back into liquid, forming clouds
  • Precipitation: water returns to Earth as rain, snow, sleet, or hail
  • Collection: water flows into bodies of water or infiltrates the ground as groundwater

Water Conservation

• Water conservation is the practice of using water efficiently
• Water conservation methods:
  • Using water-efficient appliances and fixtures
  • Reducing water usage in gardening and landscaping
  • Repairing leaks promptly
  • Practicing water-wise habits, such as taking shorter showers and turning off the tap while brushing teeth

Explore the composition and importance of air and the atmosphere. Learn about the key gases like nitrogen, oxygen, argon, and carbon dioxide, and their roles in supporting life and regulating Earth's temperature. Understand the significance of air for breathing, photosynthesis, and protection from solar radiation.