NCERT Solutions for Class 11 Chemistry Chapter 14 - Environmental Chemistry
Environmental Chemistry might seem like a straightforward descriptive chapter, but it carries significant marks in board exams and often includes application-based questions that students are unprepared for. Understanding the difference between primary and secondary pollutants, the chemistry behind the formation of smog and acid rain, the role of CFCs in ozone depletion, and the toxicological effects of heavy metals requires more than just reading - it requires understanding the underlying chemical reactions and mechanisms.
The NCERT solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry on Myclass24 are written to give you exactly that understanding. These solutions explain not just what happens but why it happens chemically - from the chain reactions of ozone destruction to the formation of biochemical oxygen demand in water bodies. For students who want to score full marks in this chapter and also develop genuine awareness about environmental issues, the detailed and accurate solutions on Myclass24 are an excellent resource.
Download NCERT Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry PDF
The PDF of NCERT Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry is freely available on Myclass24. It includes complete answers to all NCERT exercise questions on atmospheric pollution, water pollution, soil pollution, and green chemistry principles.
Chapter 14 Environmental Chemistry - Concepts, Facts and Key Tables
Environmental Chemistry studies the chemical phenomena in the natural environment and the impact of human activities on it. Chapter 14 covers four major types of pollution: atmospheric, water, soil, and introduces the concept of green chemistry as a constructive solution. One can check out all chapters of NCERT Solutions for Class 11 Chemistry and all subjects of NCERT Solutions for Class 11 from the Myclass24 page.
The atmosphere is divided into layers: troposphere (0-12 km, weather occurs here), stratosphere (12-50 km, contains the ozone layer), mesosphere (50-85 km), thermosphere (85-500 km), and exosphere. Tropospheric pollution involves gaseous pollutants - oxides of sulphur (SO2, SO3 producing acid rain), oxides of nitrogen (NO, NO2 contributing to photochemical smog), carbon monoxide (CO binds haemoglobin 200 times more strongly than O2, causing CO poisoning), hydrocarbons, and particulate matter. Global warming is primarily driven by greenhouse gases: CO2 (most significant anthropogenically), CH4, N2O, and CFCs.
Photochemical smog (Los Angeles type) forms when NOx and hydrocarbons react in sunlight to produce ozone (at ground level it is a pollutant), PAN (peroxyacetyl nitrate - a secondary pollutant irritating to eyes and lungs), and other oxidants. Classical smog (London type, sulphurous smog) forms from SO2 and particulate matter in cold, humid conditions. Stratospheric ozone depletion: CFCs (freons) are the primary culprits. In the stratosphere, UV radiation breaks CFCs to release Cl atoms, which destroy ozone in a chain reaction. One chlorine atom can destroy approximately 100,000 ozone molecules. The Montreal Protocol (1987) phased out CFC production globally.
Water pollution covers BOD (Biochemical Oxygen Demand - a measure of organic pollution; clean water less than 5 ppm, severely polluted water more than 17 ppm), heavy metal toxicity (Hg, Pb, Cd, As), eutrophication (excessive algal growth due to nutrient runoff), and fluorosis from excess fluoride. Soil pollution includes pesticides (DDT is a persistent organic pollutant), industrial effluents, and radioactive waste. Green Chemistry principles aim to design chemical processes that minimise hazardous substances at source.
Atmospheric Layers and Associated Chemistry
| Layer | Altitude | Key Chemical Feature |
| Troposphere | 0-12 km | Weather; CO2, SO2, NOx; greenhouse effect; smog formation |
| Stratosphere | 12-50 km | Ozone layer (O3 peak ~25 km); CFC-driven O3 destruction |
| Mesosphere | 50-85 km | Coldest layer; meteors burn up here |
| Thermosphere | 85-500 km | Aurora borealis; N2/O2 ionised by UV/X-rays |
Types of Smog - Comparison
| Feature | Classical (Sulphurous) Smog | Photochemical (Oxidising) Smog |
| Source | Coal/fuel burning (SO2 + soot) | NOx + hydrocarbons + sunlight |
| Climate | Cold, humid, foggy conditions | Warm, dry, sunny conditions |
| Main Pollutants | SO2, particulate matter, H2SO4 | Ground-level O3, PAN, NO2 |
| Nature | Reducing smog | Oxidising smog |
| Famous Example | London Great Smog 1952 | Los Angeles photochemical smog |
| Health Effect | Respiratory problems | Eye and lung irritation; plant damage |
Common Air Pollutants and Their Effects
| Pollutant | Major Source | Primary Effect |
| CO2 | Fossil fuel combustion | Greenhouse effect; global warming |
| CO | Incomplete combustion | Binds Hb; reduces O2 transport; lethal at high concentration |
| SO2 | Smelting, power plants | Acid rain (H2SO4); respiratory irritant |
| NO2 | Vehicle exhaust, lightning | Acid rain (HNO3); photochemical smog |
| CFCs | Refrigerants, aerosols | Ozone layer depletion; greenhouse gas |
| Particulates | Dust, smoke, pollen | Lung disease; reduces visibility |
| Pb | Leaded petrol (historical) | Neurotoxin; affects cognitive development |
FAQs for NCERT Solutions Class 11 Chemistry Chapter 14 Environmental Chemistry
Environmental chemistry is the study of chemical processes occurring in the environment and their impact on living organisms. It focuses on air, water, and soil pollution, as well as methods of environmental protection. Understanding environmental chemistry helps students analyze human activities and their effects on ecosystems. This chapter promotes awareness of sustainable practices and environmental conservation, making it highly relevant in today's world.
Air pollution is caused by the release of harmful substances such as carbon monoxide, sulfur dioxide, nitrogen oxides, particulate matter, and industrial emissions into the atmosphere. Major sources include vehicles, factories, power plants, and burning of fossil fuels. Air pollution can lead to respiratory diseases, environmental damage, and climate-related issues. Understanding its causes helps students identify preventive measures and appreciate the importance of cleaner technologies and sustainable development.
The greenhouse effect is a natural process in which certain gases trap heat in the Earth's atmosphere, maintaining a suitable temperature for life. However, excessive emissions of greenhouse gases such as carbon dioxide and methane intensify this effect, leading to global warming and climate change. Understanding the greenhouse effect helps students connect chemistry with environmental science and recognize the importance of reducing carbon emissions.
The ozone layer acts as a protective shield that absorbs harmful ultraviolet radiation from the sun. Depletion of the ozone layer increases the risk of skin diseases, eye disorders, and ecological damage. Chemicals such as chlorofluorocarbons contribute significantly to ozone depletion. Understanding the importance of ozone protection helps students learn about environmental responsibility and international efforts aimed at preserving Earth's atmosphere for future generations.