Tamilnadu Samacheer Kalvi 11th Chemistry Notes Chapter 15 Environmental Chemistry Notes

Environment – It includes the air we breathe, the water that covers most of the earth’s surface, the plants and animals around us and much more.

Environmental chemistry – It is the study of chemicals and chemical processes.

Environmental pollution – Any desirable change in our environment that has harmful effects on plants, animals and human beings is called environmental pollution.

Pollutants – The substances which cause pollution of the environment are called pollutants.

Bio-degradable pollutants – The pollutants which can be easily decomposed by the natural biological processes are called biodegradable pollutants.

Non-biodegradable pollutants – The pollutants which cannot be decomposed by the natural biological processes are called non-biodegradable pollutants.

Air – It is a mixture of 78% nitrogen, 21% oxygen, 0.93% argon, 0.04% carbon dioxide, trace amount of other gases and a little amount of water vapour.

Troposphere – The lowest layer of the atmosphere is called the troposphere and it extends from 0-10 km from the earth’s surface.

Hydrosphere – It includes all types of water sources like oceans, seas, rivers, lakes, streams, underground water, polar ice-caps, clouds and it covers about 75% of the earth’s surface.

Lithosphere – It includes soil, rocks and mountains which are the solid components of earth.

Biosphere – It includes hydrosphere, atmosphere and lithosphere.

Air pollution – Any undesirable change in air which adversely affects living organisms is called air pollution.

Gaseous air pollutants – Oxides of sulphur, oxides of nitrogen, oxides of carbon and hydrocarbons are the.gaseous air pollutants.

Greenhouse effect – It is defined as the heating up of the earth surface due to trapping of infrared radiations reflected by earth’s surface by C02 layer in the atmosphere.

Global warming – The heating up of the earth through greenhouse effect is called global warming.

Acid rain – Oxides of sulphur and nitrogen in the atmosphere are absorbed by droplets of water that make up clouds and chemically converted into sulphuric acid nitric acid and it results in the pH of rain water to become 5.6. It is called acid rain.

Stone leprosy – The extensive damage on marble by acid rain is called stone leprosy.

Particulate pollutants – They are small size biotic and aboitic solid particles and liquid droplets suspended in air. e.g., dust, pollen, smoke. Many of them are hazardous.

Viable Particulates – They are small size living organisms such as bacteria, fungi, moulds, algae which are dispersed in air.

Non-viable particulates – They are small size solid particles and liquid droplets suspended in air e.g., smoke, dust, mist, fumes.

Pneumoconiosis – The condition in which there is irritation of lungs which causes cancer and asthma by particulate pollutants is called pneumoconiosis.

Smog – It is a combination of smoke and fog which form droplets that remains suspended in air.

Classical smog on London smog – It consists of coal-smoke and fog.

Photochemical smog or Los Angeles smog – This is formed by the combination of smoke, dust and fog along with air pollutants like oxides of nitrogen and hydrocarbons in the presences of sunlight.

PAN – It stands for peroxy acetyl nitrate

Depletion of ozone – Loss of ozone molecules in the upper atmosphere is termed as depletion of stratospheric ozone.

Freons – The chlorofluro derivates of methane and ethane are called freons.

Water pollution – It is defined as the addition of foreign substances or factors like heat which degrades the quality of water, so that it becomes health hazardous or unfit for use.

Water pollutants – Microorganisms like bacteria, Viruses and protozoa acts as water pollutants.

Algal bloom – The enhanced plant growth in water bodies is called algal bloom.

Eutrophication – The process in which the nutrient rich water bodies supports a dense plant population kills animal life by depriving it of oxygen and results in loss of biodiversity is known as eutrophication.

Biochemical oxygen demand (BOD) – The total amount of oxygen in milligrams consumed by microorganisms in decomposing the waste in one litre of water at 20°C for a period of 5 days is called biochemical oxygen demand (BOD) and its value is expressed in ppm.

Chemical oxygen demand (COD) – It is defined as the amount of oxygen required by the organic matter in a sample of water for its oxidation by a strong oxidising agent like K2Cr207 in acidic medium for a period of 2 hours.

Total dissolved solids (TDS) – It includes cations like cadmium, magnesium, sodium, potassium, iron and anions like carbonate, bicarbonate, chloride, sulphate, phosphate and nitrate.

Soil – It is a thin layer of organic and inorganic material that covers the earth’s rocky surface.

Soil pollution – It is defined as the build up of persistent toxic compounds, radioactive materials, chemical salts and disease causing agents in soils which have harmful effects on plant and animal growth.

Essential Nutrients for soil – Nitrogen, Phosphorous, Potassium. (N, P, K).

Pesticides – These are the chemicals that are used to kill or stop the growth of unwanted organisms.

Irtsectides – These are the chemicals that are used to kill the insects, e.g., DDT, BLTC, Aldrin.

Fungicides – These are used to destroy fungus, e.g., Organic mercury compounds.

Herbicides – These are the chemicals used to control the growth of unwanted plants. They are also called “weedkillers” e.g., Sodium chlorate, sodium arsenite.

Industrial wastes – It may include cyanides, chromates, acids, alkalis, and metals like Hg, Cu, Zn, Cd and Pb.

Green chemistry – It is a chemical philosophy encouraging the design of products and processes that reduce or eliminates the use and generation of hazardous substances.

World environmental day – June 5

Ozone layer protection day – 16th September

Samacheer Kalvi 11th Chemistry Notes