Flashcards for JEE Chemistry - Environmental Chemistry Class 11

 Page 1


Environmental Chemistry
Flash cards
Page 2


Environmental Chemistry
Flash cards
ENVIRONMENTAL POLLUTANTS
Any substance which causes pollution in the environment is 
known as environmental pollutant. It can be atmospheric, 
water and soil pollution.
Page 3


Environmental Chemistry
Flash cards
ENVIRONMENTAL POLLUTANTS
Any substance which causes pollution in the environment is 
known as environmental pollutant. It can be atmospheric, 
water and soil pollution.
WATER POLLUTION (Continued)
The quality of drinking water is very important for human 
welfare. The pollution of water by sewage has been linked with 
the spreading of diseases such as cholera and typhoid fever.
In addition, water is also contaminated by industrial wastes, 
like :
(i) Heavy Metals : Such as Cd, Pb and Hg may be present.
(ii) Detergent and Fertilizers : They may contain PO
4
–3
as 
additives which encourages the growth of algae that reduces 
the dissolved oxygen concentration of water. This process is 
known Eutrophication.
(iii) Acid Polluted Water (pH < 3) : This is deadly to most 
forms of aquatic life.
(iv) Polychlorinated Biphenyls (PCBs) : PCBs are 
resistant to oxidation and their release into the environment 
causes skin disorders in humans. They are reported to be 
carcinogenic.
Page 4


Environmental Chemistry
Flash cards
ENVIRONMENTAL POLLUTANTS
Any substance which causes pollution in the environment is 
known as environmental pollutant. It can be atmospheric, 
water and soil pollution.
WATER POLLUTION (Continued)
The quality of drinking water is very important for human 
welfare. The pollution of water by sewage has been linked with 
the spreading of diseases such as cholera and typhoid fever.
In addition, water is also contaminated by industrial wastes, 
like :
(i) Heavy Metals : Such as Cd, Pb and Hg may be present.
(ii) Detergent and Fertilizers : They may contain PO
4
–3
as 
additives which encourages the growth of algae that reduces 
the dissolved oxygen concentration of water. This process is 
known Eutrophication.
(iii) Acid Polluted Water (pH < 3) : This is deadly to most 
forms of aquatic life.
(iv) Polychlorinated Biphenyls (PCBs) : PCBs are 
resistant to oxidation and their release into the environment 
causes skin disorders in humans. They are reported to be 
carcinogenic.
WATER POLLUTION
Determination of quality of waste water : It is done 
through BOD and COD.
Biological Oxygen demand (BOD) - It is the amount of 
oxygen required for biological oxidation by microbes in any 
unit volume of water. This test is done for at least 5 days. BOD 
values generally approximates the amount of oxidisable
organic matter.
Chemical oxygen demand (COD) : BOD measurement 
takes few days, so another parameter called COD measurement 
is required. In COD measurement sample of fixed volume is 
treated with oxidising agent (usually K
2
Cr
2
O
7
in acidic 
medium). The reagent oxidises most of the polluting 
substances including those which are resistant to microbial 
oxidation.
Page 5


Environmental Chemistry
Flash cards
ENVIRONMENTAL POLLUTANTS
Any substance which causes pollution in the environment is 
known as environmental pollutant. It can be atmospheric, 
water and soil pollution.
WATER POLLUTION (Continued)
The quality of drinking water is very important for human 
welfare. The pollution of water by sewage has been linked with 
the spreading of diseases such as cholera and typhoid fever.
In addition, water is also contaminated by industrial wastes, 
like :
(i) Heavy Metals : Such as Cd, Pb and Hg may be present.
(ii) Detergent and Fertilizers : They may contain PO
4
–3
as 
additives which encourages the growth of algae that reduces 
the dissolved oxygen concentration of water. This process is 
known Eutrophication.
(iii) Acid Polluted Water (pH < 3) : This is deadly to most 
forms of aquatic life.
(iv) Polychlorinated Biphenyls (PCBs) : PCBs are 
resistant to oxidation and their release into the environment 
causes skin disorders in humans. They are reported to be 
carcinogenic.
WATER POLLUTION
Determination of quality of waste water : It is done 
through BOD and COD.
Biological Oxygen demand (BOD) - It is the amount of 
oxygen required for biological oxidation by microbes in any 
unit volume of water. This test is done for at least 5 days. BOD 
values generally approximates the amount of oxidisable
organic matter.
Chemical oxygen demand (COD) : BOD measurement 
takes few days, so another parameter called COD measurement 
is required. In COD measurement sample of fixed volume is 
treated with oxidising agent (usually K
2
Cr
2
O
7
in acidic 
medium). The reagent oxidises most of the polluting 
substances including those which are resistant to microbial 
oxidation.
AIR POLLUTION (Continued)
Air is very essential for life, particularly oxygen which is 
needed for breathing. But at the same time air is polluted due 
to various human activities. Man made, pollutants such as 
gases like CO, NO, NO
2
, SO
2
, H
2
SO
4
, hydrocarbons and 
aerosols etc are being constantly released in the atmosphere 
leading to air pollution.
Atmospheric Pollution
Tropospheric pollution : Troposphere extends upto
height of 10 km from sea level. It contains 80% of total mass 
of air and water vapour. Pollution is also caused by SO
2
, SO
3
, 
NO
2
etc.
Stratospheric pollution : Extends (10 –50) km above sea 
level. It contains N
2
, O
2
and ozone.