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Environmental Chemistry for Higher Secondary School Chemistry

Mar 10th 2020 at 1:33 AM

Our environment deals with the social, economical, biological, physical and chemical interrelations with nature. Here we are focusing on environmental chemistry that deals with the study of chemical species in the environment. Their origin, reactions and effects are discussed here. Every individual wishes to live in a clean environment. It is important to be aware of the impact of disturbances happening in the environment. This is a very important chapter in chemistry for 11th standard students of CBSE Board. Solutions to all the questions in this chapter can be easily found in any good solution key that provides NCERT Solutions for Class 11 Chemistry. Environmental chemistry focuses on topics such as environmental pollution, global warming, greenhouse effect and acid rain. Let’s discuss some of the important issues related to the environment.

Environmental pollution

These are undesirable changes in nature affecting plants, animals and humans. There are various types of pollution in the environment such as noise, land, water, soil,air etc. The harmful substances that cause pollution are known as pollutants. These pollutants remain in an unchanged form in nature for many decades. For example pollutants such as DDT, chemical and nuclear wastes, plastics, and heavy metals are difficult to remove from the environment.

Atmospheric pollution

These pollution are generally studied as tropospheric and stratospheric pollution. The presence of ozone in the stratosphere prevents the harmful UV rays entering the earth surface. And it protects the living organisms on the earth.

Tropospheric pollutants consists of:

  1. Gaseous air pollutants: sulphur, nitrogen, carbon, hydrocarbons, hydrogen sulphide and other oxidants
  2. Particulate pollutants: dust, mists, fumes, smoke, smug etc.

Global warming

Solar energy that reaches the earth’s surface is absorbed that increases the temperature. And the rest of the heat radiates back to the atmosphere. Some heat is trapped by gases such as carbondioxidem methane, ozone, chlorofluorocarbon compounds in the atmosphere. These compounds increase the heat in the atmosphere called global warming.

Acid rain

Usually the normal ph of rain is 5.6 due to the presence of hydrogen ions formed by the reaction of rain water and carbon dioxide. But when the ph value decreases to 5.6 it is called acid rain.

Acid rains are caused due to human activities that release oxides of sulphur and nitrogen in the atmosphere. The sulphur and nitrogen are released by burning fossil fuels in the environment.

Particulate pollutants

These are minute solid or liquid particles in the air. It is in the form of vehicle emission, smoke particles, ash, etc. They are viable and non viable. The viable sources are bacteria, fungi, algae etc. The non viable sources are smoke particles, dust,mists, fumes, smog etc.

Many human activities are producing harmful chemicals that are responsible for the depletion of ozone layer. This causes an ozone hole that allows the harmful ultraviolet rays to enter the earth’s surface.

Water pollution

Water is essential for life. The water resources are getting contaminated due to harmful substances discharged in the water bodies. The water pollution is caused due to pathogens, organic wastes and chemical pollutants. Chemicals are disposed of at a high level in the water from the industries. Many chemicals such as cadmium, mercury,and nickel are discharged into the water. As these chemicals are very dangerous to humans as they cannot excrete them.

Likewise there are also other factors that are involved in the pollution are soil and industry wastes.

Strategies to control environmental pollution

  1. Waste management- solid and wet waste should be segregated. The improper disposal of waste is the important reason that causes environmental degradation.
  2. Collection and disposal- the waste is segregated into biodegradable and non biodegradable. The biodegradable waste like leaves, vegetable waste, leftover food etc are used for compost. Whereas non biodegradable waste is sent for recycling.
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