CLASS 11 chemistry ch 14

Class 11 chemistry chapter 14

Environmental Chemistry

For CBSE Notes of Class 11

Environmental chemistry deals with the study of the origin,transport,reactions,effects,fates of chemical species in the environment.

ENVIRONMENTAL POLLUTION

Environmental pollution is the effect of undesirable changes in our surroundings that have harmful effects on plants, animals and human beings.A substance which causes pollution is called a pollutant.they can be solid,liquid or in the gaseous state.

  ATMOSPHERIC POLLUTION

The atmosphere that surrounds the earth is not of the same thickness at different heights.Atmospheric pollution is generally studied as tropospheric and stratospheric pollution.The ozone layer prevents about 99.5%of the sun’s UV rays.

  TROPOSPHERIC POLLUTION

Tropospheric pollution occurs due to the presence of undesirable solid  or  gaseous particles in the air. The following are the major gaseous and particulate pollutants present in the troposphere;

•  Gaseous air pollutants:These are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.

•  Particulate  pollutants; these are dust, mist, fumes, smoke, smog etc

  GLOBAL WARMING AND GREENHOUSE EFFECT

About 75% of the solar energy reaching the earth is absorbed by the earth’s surface,which increases it’s temperature.The rest of the heat radiates back to the atmosphere.Some of the heat is trapped by the gases such as carbon dioxide,methane,ozone,CFCS and Water vapour.they add to the heating of the atmosphere causing Global warming In a greenhouse,visible light passes through the transparent glass and heats up the soil and the plants.The warm soil and plants emit infrared rays,it partly reflects and partly absorbs these radiations,this mechanism keeps the energy of the sun trapped in the greenhouse.

  ACID RAIN

When the pH of the rain water drops below5.6, it is called acid rain.Acid rain is harmful for agriculture, trees and plants as it dissolves and washes away nutrients needed for their growth. It causes respiratory ailments in human beings and animals. When acid rain falls and flows as ground water to reach rivers, lakes etc. it affects plants and animal life in aquatic ecosystem

SMOG

 The word smog comes from smoke and fog.  There are two types of fog: conventional smog and photochemical smog.  Classic smog occurs in cool, humid climates.  It is a mixture of smoke, fog and sulfur dioxide.  It is also called reducing cigarettes.  Meanwhile, photochemical fog occurs in hot, dry climates.  It has a high concentration of oxidizing substances, and therefore it is also called oxidizing mist.

  OZON HOL

 The depletion of the ozone layer is called the depletion of the ozone layer.

  The consequences of the placement of the ozone layer

 As the ozone layer decays, more UV filters are transferred to the troposphere.  UV rays cause skin aging, cataracts, sunburn, skin cancer, the death of many phytoplankton and damage to fish productivity.

  YOUR PRODUCTION

 Pollution of water by foreign substances, harmful to the health or life of animals, plants or water, makes it unfavorable for domestic, industrial and agricultural use.

  W Ր I Sources / reasons for the solution

 Wastewater and household waste Industrial emissions Agricultural emissions Heating of soil or rock water Thermal pollutants Radioactive emissions

  EUTROPHICATION-

 The process by which nutrient-rich aquatic organisms support dense vegetation, which destroys animals' lives by depriving them of oxygen and causing further loss of biodiversity, is known as eutrophication.

  PEOPLE:

 The amount of oxygen required for bacteria containing organic matter in a certain volume of the bacteria sample is called the biochemical oxygen demand (BOD).

  Earth pollution

 Herbicides, herbicides and herbicides cause soil contamination.

 Green chemistry

 Green chemistry is a way for us to reflect on existing knowledge and principles of chemistry and other sciences to reduce the negative impact on the environment.  The basis of existing knowledge on chemical risk reduction, as well as the development of activities, is the basis of green chemistry.