Environmental Chemistry Class 11th Notes - Free NCERT Class 11 Chemistry Chapter 14 Notes - Download PDF

Because it deals with environmental topics from a chemical standpoint, Environmental Chemistry is an important chapter for students in Class 11. Class 11 Chemistry chapter 14 notes discuss the study of reactions, their origins, and effects, as well as the overall fate of species in the ecosystem. Furthermore, the topics covered in this chapter are vast, and students may not recollect all of the information, which may impede their productivity.

Taking this into consideration CBSE Class 11 Chemistry chapter 14 notes is prepared in the simplest form. , notes for Class 11 Chemistry chapter 14 provide solid and thorough knowledge of all the related areas. The information provided is also relevant and to the point, and these notes will serve as a valuable resource for fully comprehending the chapter. Additionally, students will be able to study more effectively and achieve greater grades on their exams. For more information on any of the topics presented in this chapter, students can refer to the following references.

Also, students can refer,

• NCERT Notes Class 11 Chemistry
• NCERT Solutions for class 11 Chemistry Chapter 14 Environmental Chemistry
• NCERT Exemplar Class 11 Chemistry Chapter 14 Solutions Environmental Chemistry

NCERT Class 11 Chemistry Chapter 14 Notes

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 1

Environmental Pollution

• Environmental chemistry is the discipline of chemistry that studies the chemical phenomena that occur in the environment.

• Environmental pollution can be defined as the undesirable change of the environment with hazardous wastes, primarily as a result of human activity.

• These activities emit contaminants into the atmosphere, water, and soil, damaging them.

Pollutant

Pollutant is a substance that causes pollution. A pollutant is a material that is released by a natural source or by human activity that has a negative impact on the environment.They are of two types

• Biodegradable pollutant

Biodegradable pollutants are pollutants that can be destroyed by biological or microbiological action. Eg: domestic sewage

• Non biodegradable pollutant

Non-biodegradable pollutants are chemicals that are not generally acted upon by bacteria. These results in biomagnification. Eg: DDT

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 2

Atmospheric Pollution

When the concentration of a natural component of the air, or a new chemical substance added or generated in the air, reaches unacceptably high levels, it harms humans, animals, flora, and materials. This is referred to as atmospheric pollution. It is mainly of two types

1. Tropospheric pollution

2. Stratospheric pollution

Tropospheric pollution

The presence of unwanted solids or gaseous particles in the atmosphere causes tropospheric pollution. Gaseous contaminants and particulate particles cause this condition

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 3

Gaseous Air Pollutants

• Oxides of sulfur

Sulfur dioxide (SO₂) is the most common species. Petrol combustion, coal combustion, petrol refining, and smelting processes all contribute to its production. It obstructs airflow into and out of the lungs. It's especially toxic to trees, inducing chlorosis and dwarfing. It is oxidized to SO3in the presence of air, which is also an irritant. The Taj Mahal is said to be harmed by SO2and other pollutants emitted by the Mathura oil refinery.

2 SO₂g+O₂ g → 2 SO₃

SO₂g+O₃ g → SO₃+O₂ g

SO2g+H₂O₂(l) → H₂SO₄(aq)

• Oxides of nitrogen

Coal, gasoline, natural gas, petroleum refining, chemical industries, and cigarette smoke all produce NO2 and NO respectively. High-altitude jets and rockets produce these in the upper atmosphere.

N2g+O2g 1483 K→ 2 NO (g)

2 NO+O_2(g) → 2NO₂

Plants get chlorosis as a result of breathing NO2, and humans have chronic lung diseases that lead to mortality. Ozone depletion is caused by these oxides.

NO (g) + O₃g → NO₂+O₂

• Hydrocarbons

• Incomplete combustion of fossil fuels in industrial and thermal power plants, as well as automobile exhaust, releases hydrocarbons into the atmosphere and thereby polluting the environment. They are carcinogenic. They affect plants in a variety of ways, including tissue collapse and leaf shedding. Methane is a greenhouse gas.

• Oxides of carbon

• Carbon monoxide CO

Carbon monoxide (CO) is a colourless, odourless gas. Incomplete combustion of gasoline in automobiles, wood, coal, incineration, and forest fires all produce it. It forms carboxyhaemoglobin with haemoglobin, which is more stable than the oxygen-haemoglobin combination. When its concentration in the blood reaches 3-4 percent, the blood's oxygen carrying ability is severely diminished. A lack of oxygen causes headaches, blurred vision, anxiety, and other symptoms. When the concentration is high enough, it has negative effects on plants (100 ppm or more).

• Carbon dioxide CO₂

By volume, 0.03 percent CO₂ is present in the air. The combustion of fossil fuels, the disintegration of limestone during the making of cement, and volcanic eruptions are all major sources. Deforestation and the use of fossil fuels raise the level of CO2, which is the primary cause of global warming.

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 4

Global Warming and Greenhouse Effect

Some gases, such as carbon dioxide, methane, ozone, water vapours, and CFCs, can capture some of the heat radiations emitted by the earth or the sun. The impact is known as the greenhouse effect, and these gases are known as greenhouse gases. As a result, global warming occurs. Carbon dioxide is the major contributor to global warming.

Consequences

• It causes polar ice caps to melt and low-lying places around the world to flood.

• As the world's temperature rises, infectious diseases such as dengue fever, malaria, yellow fever, and sleeping sickness become more common.

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 5

Acid Rain

Acid rain occurs when the pH of the rainwater falls below 5.6.Due to the solubility of atmospheric carbon dioxide in water, normal rain is slightly acidic.

H₂O+CO₂ ↔ H₂CO₃

H₂CO₃ ↔ H⁺+HCO₃^-

Nitric acid and sulphuric acid are formed when nitrogen and sulphur oxides produced by the burning of fossil fuels dissolve in water.

2 SO₂+O₂+2 H₂O →2H₂SO₄

4 NO₂+O₂+2H₂O → 4HNO₃

Harmful effects

• It harms trees and plants by dissolving and wiping away nutrients necessary for their growth.

• It has a negative impact on aquatic ecology.

• Acid rain causes harm to stone and metal buildings and structures. Acid rain has harmed the Taj Mahal in India.

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 6

Particulate Pollutants

Particulate pollution are airborne solid particles or liquid droplets that are too small to see. Fine particles with a diameter of less than 5 microns can enter the lungs. Such particles can cause significant lung disorders, including lung cancer, if inhaled. Larger suspended particles can prevent sunlight from reaching the earth's surface. This can cause the earth's temperature to drop and the weather to become cloudy. Particulate pollutants are of two types

• Viable: They are microscopic living things that float around in the air. Bacteria, fungi, moulds, algae, and other microorganisms are examples

• Non viable:They include:-

Smoke-Smoke is a mixture of solid and liquid particles created by the combustion of organic materials, such as cigarette smoke or smoke from fossil fuel combustion.

Dust-Dust is made up of small solid particles (over 2gm in diameter). It is made when solid particles are crushed, ground, and dispersed.

Mist-Mist is formed when liquids such as herbicides and insecticides are sprayed on plants. They fly through the air and condense into mist.

Fumes-Fumes are emitted into the atmosphere by metallurgical processes as well as a variety of chemical reactions.

Smog

This is the most frequent type of air pollution, and it consists of a mixture of smoke and fog.

1. Classical smog

Smog that occurs in a cold, humid area is known as classic smog. It contains sulfur dioxide, smoke, and fog. It is also known as reducing smog.

2. Photochemical smog

Photochemical smog is caused by sunlight reacting with unsaturated hydrocarbons and nitrogen oxides. It is referred to as oxidizing smog because it has a high concentration of oxidizing chemicals.

Formation

NO₂ hϑ→NO+O

O+O₂ ↔ O₃

NO+O₃ → NO₂+O₂

Ozone reacts with unburnt hydrocarbons in polluted air and produces chemicals such as formaldehyde, acrolein, peroxyacetyl nitrate (PAN) etc.

Effects

Photochemical smog can induce cough, bronchitis, and respiratory system inflammation, among other things. To combat this sort of pollution, automobile engines are equipped with catalytic converters that limit the release of both nitrogen oxides and hydrocarbons into the atmosphere. Some plants, such as Vitis, Pinus, Juniperus, Quercus, and Pyrus, can metabolize nitrogen oxide can be planted.

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 7

Stratospheric Pollution

Formation and breakdown of ozone

UV radiation generates ozone in the stratosphere. Ozone is formed when UV rays interact with dioxygen (O2) molecules.

O₂ hϑ→ O+O

O+O₂ UV↔ O₃

Ozone decomposes to molecular oxygen and is thermodynamically unstable. As a result, there is a balance between the formation and destruction of ozone molecules.

The ozone layer in the upper atmosphere keeps dangerous UV rays from reaching the earth. However, there have been indications in recent years of this layer being depleted due to the presence of certain chemicals in the stratosphere. Depletion is caused by substances such as chlorofluorocarbons (CFCs), nitrogen oxides, chloride, CCl₄, and others.

CF₂Cl₂ UV→ Cl+C F₂Cl

Cl +O₃ →ClO +O₂

ClO+O → Cl+ O₂

In the presence of light, chlorofluorocarbons dissociate into chlorine free radicals, which catalyze the conversion of ozone to oxygen.

Effect of depletion of ozone layer

• Depletion in ozone layer causes several problems like several problems such as skin cancer, sunburn, skin ageing, cataracts

• UV rays can kill a large number of phytoplanktons, reducing fish productivity

• It can reduce the moisture content of the soil by promoting surface water evaporation.

• UV rays can harm paints and fibres, causing them to fade more quickly.

NCERT Class 11 Chemistry Chapter 8 Notes: Topic 8

Water Pollution

Water pollution is defined as the presence of undesired components in water that are damaging to humans and plants. The presence of these foreign materials can alter the water's normal qualities.

Causes of water pollution

• Pathogens

Pathogens are bacteria and other organisms that enter water through residential waste and animal waste. Bacteria such as E. coli and Streptococcus faecalis can be found in human excreta. It causes gastrointestinal problems.

• Organic wastes

Organic wastes, such as leaves, grass, rubbish, and other organic debris, can pollute water. Excessive phytoplankton growth in water also pollutes it. By digesting organic waste in water, large numbers of bacteria can consume oxygen dissolved in the water. Fish growth is slowed when the concentration of dissolved oxygen in the water falls below 6 parts per million. When too much organic stuff is added to water, the oxygen supply is depleted. This may result in the death of aquatic life.

• Chemical pollutants

Chemical reactions in industrial units pollute water to a large extent. Lead, mercury, nickel, cobalt, and other metals are examples. Pesticides include chlorinated hydrocarbons, organophosphates, and metallic salts, among others that pollute water by dissolving to a little extent in it. Pesticides are harmful to both plants and animals because they are all poisonous in nature. PCBS (polychlorinated biphenyls) are chemical substances that are utilized as fluids in transformers and capacitors. These are emitted as vapours into the atmosphere. They contaminate the water when they combine with rainwater. Eutrophication is the process by which algae-like organisms diminish the amount of dissolved oxygen in water. It is hazardous to aquatic life.

Biochemical oxygen demand (BOD)

It is the quantity of oxygen needed by bacteria to break down the organic materials in a given volume of water. BOD in water is a measurement of the amount of organic matter in the water. The BOD value of clean water is less than 5 ppm. Water with a BOD value of 17 ppm or more is considered highly contaminated.

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 9

Soil Pollution

The addition of chemicals in an uncontrolled proportion alters the soil's productivity. This is referred to as "soil pollution" or "land pollution."

Sources

• Insecticides

Chlorinated hydrocarbons, such as DDT and BHC, are the most common pesticides. They stay in the soil for a long time since they are not water soluble. They are absorbed by the soil and contaminate root crops such as radish, carrot, and other root vegetables.

• Herbicides

These are the chemicals that are used to control weeds. Sodium chlorate (NaClO3) and sodium arsenite (Na3AsO3 )are two typical herbicides, however arsenic compounds are no longer favoured due to their toxicity.

• Fungicides

The most popular fungicides are organomercury compounds. When it dissociates in the soil, mercury is released, which is very poisonous and detrimental to crops.

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 10

Strategies to Control Environmental Pollution

• Waste management: One of the biggest causes of environmental damage is poor waste disposal. The proper disposal of garbage is important.

• Collection and disposal:All household garbage should be collected and disposed of correctly.

NCERT Class 11 Chemistry Chapter 14 Notes: Topic 12

Green Chemistry

Green chemistry is a way of thinking about using chemical knowledge and principles to reduce environmental damage.

Green chemistry in daily life

• Dry-Cleaning of clothes and laundry:Replacement of halogenated solvents like (CCl₄) with liquid CO₂, which is less damaging to groundwater, in dry-cleaning of garments and laundry.

• Paper Bleaching: Instead of chlorine, H₂O₂ is used to bleach paper.

• Chemical Synthesis: Ethanal (CH₃CHO) is made by oxidizing ethene

CH₂=CH₂+O₂ PdII in water→CH₃CHO (90%)

Significance of NCERT Class 11 Chemistry Chapter 14 Notes

The chapter is pretty long, and there are a lot of terms to understand. Furthermore, there are several details that students may find difficult to grasp. NCERT notes for Class 11 Chemistry chapter 14 offers students a simple and brief overview of the chapter Class 11 Environmental Chemistry. It is designed in way that is helpful for both board exams and other competitive examinations. Students can use Class 11 Chemistry chapter 14 notes pdf download for their offline study. From Environmental Chemistry Class 11 pdf download students can download the notes and use it for their exam preparations.

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