Graduate
  1. Physical Chemistry  1.1. Thermodynamics  1.1.1. Laws of Thermodynamics  1.1.2. Enthalpy and heat capacity  1.1.3. Entropy and free energy  1.1.4. Phase Equilibrium  1.1.5. Statistical thermodynamics  1.1.6. Thermodynamic cycle  1.1.7. Fugacity and activity  1.2. Quantum Chemistry  1.2.1. Principles of quantum mechanics  1.2.2. Schrödinger Equation  1.2.3. Particle in a box  1.2.4. Operators and eigenvalues  1.2.5. Atomic orbitals  1.2.6. Molecular orbital theory  1.2.7. Perturbation theory  1.2.8. Valence bond theory  1.2.9. Hybridization and chemical bonding  1.3. Chemical kinetics  1.3.1. Rate laws and reaction mechanisms  1.3.2. Collision theory  1.3.3. Transition state theory  1.3.4. Enzyme Kinetics  1.3.5. Chain Reactions and Polymerization  1.3.6. Photochemical reactions  1.4. Statistical mechanics  1.4.1. Partitioning functions  1.4.2. Molecular distribution functions  1.4.3. Boltzmann Distribution  1.4.4. Bose–Einstein and Fermi–Dirac statistics  1.5. Spectroscopy  1.5.1. Rotational Spectroscopy  1.5.2. Vibrational Spectroscopy  1.5.3. Electronic Spectroscopy  1.5.4. Nuclear magnetic resonance spectroscopy  1.5.5. Mass Spectrometry  1.5.6. Raman Spectroscopy  1.5.7. Electron paramagnetic resonance spectroscopy  1.6. Surface and colloidal chemistry  1.6.1. Absorption isotherm  1.6.2. Surface tension and wetting  1.6.3. Colloidal Stability  1.6.4. Catalysis  1.6.5. Emulsions and micelles  1.7. Electrochemistry  1.7.1. Nernst equation  1.7.2. Electrochemical cells  1.7.3. Conductivity and mobility  1.7.4. War  1.7.5. Fuel cells  1.7.6. Electrolysis
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic reactions  2.2. Spectroscopy and structural determination  2.2.1. UV-Vis Spectroscopy  2.2.2. IR Spectroscopy  2.2.3. NMR Spectroscopy  2.2.4. Mass Spectrometry  2.2.5. X-ray crystallography  2.3. Stereoscopic  2.3.1. Chirality and optical activity  2.3.2. Structural analysis  2.3.3. Geometrical isomerism  2.3.4. Dynamic Stereochemistry  2.4. Organometallic Chemistry  2.4.1. Organolithium and organomagnesium reagents  2.4.2. Palladium-catalyzed cross-coupling reactions  2.4.3. Transition Metal Complexes  2.4.4. Metal–carbon bond  2.5. Polymer chemistry  2.5.1. Polymerization mechanism  2.5.2. Polymer Characteristics  2.5.3. Biodegradable Polymer  2.5.4. Conducting polymer  2.5.5. Supramolecular polymers  2.6. Medicinal chemistry  2.6.1. Drug design and development  2.6.2. Pharmacokinetics and pharmacodynamics  2.6.3. Structure-activity relationships  2.6.4. Molecular docking and drug screening
  3. Inorganic chemistry  3.1. Coordination chemistry  3.1.1. Crystal field theory  3.1.2. Ligand field theory  3.1.3. Spectrochemical Series  3.1.4. Chelation and stability  3.2. Organometallic Chemistry  3.2.1. Metal Carbonyls  3.2.2. Catalysis by organometallic complexes  3.2.3. Metallocenes  3.3. Bio-inorganic chemistry  3.3.1. Metalloproteins and enzymes  3.3.2. The role of metals in biological systems  3.3.3. Metal ion transport and storage  3.4. Solid state chemistry  3.4.1. Crystal Structures  3.4.2. Band theory of solids  3.4.3. Superconductors  3.4.4. Defects in the crystal  3.5. Lanthanides and Actinides  3.5.1. Electronic configuration in lanthanides and actinides  3.5.2. Coordination chemistry of the lanthanides  3.5.3. Magnetic Properties of Lanthanides
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.2. Spectroscopic Techniques  4.2.1. Atomic absorption spectroscopy  4.2.2. X-ray diffraction  4.2.3. Inductively coupled plasma spectroscopy  4.3. Electroanalytical methods  4.3.1. Potentiometry  4.3.2. Voltammetry  4.3.3. Colometry  4.4. Mass Spectrometry  4.4.1. Ionization Technique  4.4.2. Fragmentation Pattern  4.5. Chemometrics  4.5.1. Multidisciplinary analysis  4.5.2. Machine Learning in Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.1.1. Force fields and energy minimization  5.1.2. Monte Carlo simulation in molecular dynamics simulations  5.2. Quantum chemical methods  5.2.1. Hartree–Fock theory  5.2.2. Density functional theory  5.2.3. Semi-empirical methods  5.3. Computational drug design  5.3.1. Molecular Docking  5.3.2. QSAR Modeling  5.3.3. Virtual Screening
  6. Biochemistry  6.1. Enzyme Kinetics  6.1.1. Michaelis-Menten kinetics  6.1.2. Inhibition mechanism  6.2. Metabolism and Bioenergetics  6.2.1. Glycolysis  6.2.2. Citric acid cycle  6.2.3. Electron transport chain  6.3. molecular Biology  6.3.1. DNA replication and repair  6.3.2. Protein synthesis  6.3.3. Gene Regulation  6.4. Structural Biochemistry  6.4.1. Protein Folding  6.4.2. Membrane Biophysics
  7. Environmental Chemistry  7.1. Atmospheric Chemistry  7.1.1. Greenhouse gases  7.1.2. Ozone depletion  7.1.3. Air pollutants and smoke  7.2. Water Chemistry  7.2.1. pH and water hardness  7.2.2. Wastewater treatment  7.2.3. Aquatic Chemistry  7.3. Soil Chemistry  7.3.1. Heavy metal contamination  7.3.2. Soil pH and Buffering  7.3.3. Nutrient cycling  7.4. Toxicology and Chemical Safety  7.4.1. Toxicokinetics  7.4.2. Risk Assessment in Toxicology and Chemical Safety in Environmental Chemistry  7.4.3. Effects of pollutants on the environment

Graduate → Environmental Chemistry → Atmospheric Chemistry ↓


Air pollutants and smoke


Air pollution is a serious environmental issue that affects ecosystems, human quality of life, and even global climate patterns. The primary factors of air pollution include air pollutants and smog, both of which are important components in the study of atmospheric chemistry within the broader environmental chemistry field. Understanding air pollutants and smog involves taking a deeper look at their sources, chemical composition, environmental effects, and control measures.

Air pollutants

Air pollutants are substances present in the atmosphere that can harm living organisms or damage the natural environment. They can be classified into two major categories: primary pollutants and secondary pollutants.

Primary pollutants

Primary pollutants are emitted directly from the source. Sources may be natural, such as volcanic eruptions or forest fires, or anthropogenic, such as vehicle emissions or industrial activities. The main types of primary pollutants include:

  • Carbon monoxide (CO): A colourless and odourless gas formed by the incomplete combustion of carbon-containing fuels. It is highly toxic and can harm humans and animals by preventing adequate oxygen supply to the body's organs and tissues.
  • Sulfur dioxide (SO2): This gas is emitted mainly from the burning of fossil fuels in power plants and industrial facilities. It can react with water vapor to form sulfuric acid, which causes acid rain.
  • Nitrogen oxides (NOx): A group of reactive gases including nitric oxide (NO) and nitrogen dioxide (NO2). These gases are emitted from vehicular and industrial activities and play an important role in the formation of ground-level ozone and smog.
  • Particulate matter (PM): Particulate matter is tiny particles or droplets suspended in the air. PM can consist of a variety of substances, including dust, soot, and liquid droplets.

Secondary pollutants

Secondary pollutants are not emitted directly. Instead, they are formed in the atmosphere through chemical reactions of primary pollutants. Examples include:

  • Ozone (O3): At ground level, ozone is harmful to human health. It is formed by the reaction of NOx with volatile organic compounds (VOCs) in the presence of sunlight.
  • Sulfuric acid (H2SO4): Produced from the oxidation of sulfur dioxide, it is a major component of acid rain.
  • Nitrate and sulfate aerosols: These tiny particles contribute to air pollution and can be hazardous to health. They are formed through complex reactions involving sulfur dioxide and nitrogen oxides.

An important visual representation of how pollutants such as NOx and VOCs are converted into ozone is shown below:

    NOx + VOCs + sunlight → O3
sunlight Nox VOCs O3

Haze

Smog is a specific type of air pollution that is a visible presence of particles and other pollutants in the air. It is mainly classified into two types: classical smog and photochemical smog.

Classic smoke

Classical smog, also known as "London smog," is a blackish-brown haze of air caused primarily by high concentrations of sulfur dioxide and particulate matter. This type of smog was particularly problematic in industrial cities during the 19th and 20th centuries, when coal burning was prevalent.

The chemical composition of classical fog can be represented as follows:

    SO2 + PM → classical smog

Photochemical smog

This type of smog is more common in modern urban environments and is the result of the action of sunlight on nitrogen oxides and volatile organic compounds. Photochemical smog is often characterized by a brown haze and is common in places with warm climates and abundant sunlight.

Photochemical smog formation involves a number of complex reactions, including:

    NO2 + sunlight → NO + O
    O + O2 → O3

This sequence can result in increased concentrations of ozone at ground level, which can lead to smog.

A visual depiction of the formation of photochemical smog is given below:

sunlight No2 No O3

Effects on health and environment

Both air pollutants and smoke have a significant impact on human health and the environment. The consequences of exposure to such pollutants are wide-ranging.

Effects on health

  • Exposure to high levels of CO can reduce the supply of oxygen to the body's organs and tissues, causing symptoms such as headache, dizziness, and, in severe cases, death.
  • SO2 and NOx can cause respiratory problems such as asthma and bronchitis.
  • Particulate matter (PM) can penetrate deep into the lungs and cause cardiovascular and respiratory diseases.
  • It is beneficial in the ozone layer, but it is harmful at ground level and can cause chest pain, cough, and sore throat.

Environmental impact

  • Air pollution can cause acid rain, which has harmful effects on soil, water bodies, and vegetation.
  • Haze can reduce visibility and cause damage to crops, natural vegetation, and materials.
  • Air pollutants can destroy wildlife habitats and harm biodiversity.
  • Long-term exposure to certain pollutants can cause climate change.

Control measures

Tackling air pollution requires a range of strategies, from regulatory measures to technological innovations. Some common measures are as follows:

  • Regulation and legislation: Governments can impose limits on emissions from vehicles and industrial sources.
  • Technology enhancement: Use of clean technologies and renewable energy sources to reduce dependence on fossil fuels.
  • Pollution control devices: Implementation of filters, scrubbers, and catalytic converters to minimise emissions.
  • Public awareness: Educating the public about the sources and hazards of air pollution promotes behavioral change that reduces pollution.

Conclusion

Air pollution, particularly in the form of air pollutants and smog, presents significant threats to the environment and human health. A comprehensive understanding of the chemistry behind the formation of these pollutants and smog is critical for effective management and mitigation strategies. Continued research and societal commitment to reduce emissions and adopt clean energy sources will be critical in addressing the challenges posed by air pollutants and smog.


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Air pollutants and smoke

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