A slide based on chemistry

1. MOHIT RANA
CLASS XI

2. INDEX
 INTRODUCTION
 ENVIRONMENT POLLUTION
 ATMOSPHERIC POLLUTION
TROPOSPHERIC POLLUTION
 GLOBAL WARMING
ACID RAIN
SMOG
THE OZONE HOLE
WATER POLLUTION
INTERNATIONAL STANDARDS FOR DRINKING WATER
 SOIL POLLUTION
 WASTE DUMPING
STRATEGIES TO CONTROL ENVIRONMENTAL DAMAGE

3. •INTRODUCTION
•The term “Environment” literally means
“surrounding”.
It comprises of the following four major
components:
(1) Atmosphere, (2) Hydrosphere, (3) Lithosphere
and (4) Biosphere.
• “ENVIRONMENT CHEMISTRY” is a branch of
science
which deals with the chemical phenomena occurring
in
the environment, i.e., study of origin, transport,
reactions, effects and fates of chemical species in
the

4. •Environment Pollution
•“Environment pollution” is the effect of undesirable
changes in our surroundings that have harmful
effects
on the plants, animals and human beings. A
substance,
which causes pollution , is known as “pollutant”.
Pollutants can be solid, liquid or gaseous
substances
present in the greater concentration than in natural
abundance and are produced due to human
activities or
due to natural happenings.

5. ATMOSPHERIC POLLUTION
Air pollution is defined as the addition of undesirable
materials
into the atmosphere either due to natural phenomena or due
to
human activity on the earth which adversely affect the quality
of
the air and hence affects the life on the earth. It is also known
as
“Atmospheric Pollution”
Atmospheric pollution is generally studied as Tropospheric
and Statospheric pollution.

6. •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:
1.Gaseous air pollutants: These are oxides of
sulphide,
hydrocarbons, ozone and other oxidants.
2.Particulate pollutants: These are dust, mist, fumes,
smoke, smog etc.

7. 1.Gaseous Air Pollutants
(a) Oxides of Sulphur
Oxides of sulphur are produced when sulphur
containing fossil fuel is burnt. The most common
species, sulphur dioxide, is a gas that is poisonous
to both animals and plants. It has been reported that
even a low concentration of sulphur dioxide causes
respiratory diseases. However, the presence of
particulate matter in polluted air catalysts the
oxidation of sulphur dioxide to sulphur trioxide.
2SO2 (g) + O2 (g) → SO3 (g)
SO2 (g) + O3 (g) → SO3 (g) + O2 (g)
SO2 (g) + H2O2 (l) → H2SO4 (as)

8. (b) Oxides of Nitrogen
Dinitrogen and dioxygen are the main constituents
of
air. These gases don’t react with each other at a
normal temperature. At high altitudes when lightning
strikes, they combine to form oxides of nitrogen.
NO2
is oxidized to nitrate ion. When fossil fuel is burnt,
dinitrogen and dioxygen combine to yield significant
quantities of nitric oxide (NO) and nitrogen dioxide
(NO2).
N2 (g) + O2 (g) → 2NO (g) [at 1483K]
2NO (g) + O2 (g) → 2NO2 (g)
NO (g) + O3 (g) → NO2 (g) + O2 (g)

9. (c) Hydrocarbons
Hydrocarbons are composed of hydrogen and carbon
only and are formed by incomplete combustion of fuel
used in automobiles. Hydrocarbons are carcinogenic,
i.e., they cause cancer. They harm plants by causing
ageing, breakdown of tissues and shedding of leaves,
flowers and twigs.
(d) Oxides of Carbon
(i) Carbon monoxide: Carbon monoxide is one of the
most serious air pollutants. It is a colorless and
odorless gas, highly poisonous to living beings because
of its ability to block the delivery of oxygen to the organs
and tissues. It is mainly released by automobiles. It
binds to haemoglobin to form carbon haemoglobin,
which is about 300 times more stable than the
oxygen-haemoglobin complex. This results in headache,

10. weak eyesight, nervousness and cardiovascular
disorder.
(ii) Carbon dioxide: Carbon dioxide is released into
the
atmosphere by respiration, burning of fossil fuels for
energy, and by decomposition of limestone during
the
manufacture of cement. Normally it is about 0.03%
by
volume of the atmosphere. Green plants need
carbon
dioxide for photosynthesis and they, in turn, emit
oxygen, thus maintaining the delicate balance. The
increase in mount of carbon dioxide in the air is

11. •Global Warming&
Greenhouse Effect
• About 75% of the solar energy reaching the earth is
absorbed by the earth’s surface, which increases its
temperature. The rest of the heat radiates back to
the atmosphere. Some of the heat is trapped by
gases like carbon dioxide, methane, ozone,
chlorofluorocarbon compounds (CFCs) and water
vapour in the atmosphere. Thus, they add to the
heating of the atmosphere. This causes “Global
Warming”.
• Just as the glass in a greenhouse holds the sun’s
heat near the earth’s surface and keeps it warm. This
is called natural greenhouse effect.

12. Causes of Global Warming
•Increase in concentration of carbon dioxide
which is emitted by automobiles, industries,
etc,.
•Increase in concentration of methane which
is emitted when vegetation is burnt, paddy
fields, coal mines etc,.
•Increase in concentrations of CFCs which is
commonly produced or emitted by
refrigerators, A.C.s, etc,.

13. ACID RAIN
• We are aware that normally rain water has a pH of 5.6
due to presence of Hydrogen ions formed by reaction
of rain water with carbon dioxide present in the
atmosphere.
H2O (l) + CO2 (g) ↔ H2CO3 (aq)
H2CO3 (aq) ↔ H+ (aq) + HCO3− (aq)
• When the pH of the rain water drops below 5.6, it is
called acid rain. Oxides of sulphur and nitrogen in the
atmosphere produces acid rain. Burning of fossil fuels
such as coal and oil in power stations or petrol and
diesel in motor engines produce SO2 and NO2 after
oxidation and reaction with water are major
contributors to acid rain.
• 2SO2 (g) + O2 (g) + H2O (l) → 2H2SO4 (aq)

14. • 4NO2 (g) + O2 (g) + H2O (l) → 4HNO3 (aq)
• Results of 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. It corrodes water pipes
resulting in the leaching of heavy metals such as
iron, lead and copper into drinking water.

15. 2.PARTICULATE POLLUTANTS
• Particulates pollutants are the minute solid
particles
or liquid droplets in air. These are present in vehicle
emissions, smoke particles from fires, dust particles
and ash from industries. Particulates in the
atmosphere may be viable or non-viable. The viable
particulates e.g., bacteria, fungi, moulds, algae etc.,
are minute living organisms that are dispersed in the
atmosphere. They cause plant diseases.
• Non-viable particulates can be classified according
to
their size and nature as follows:
(a) Smoke particulate consist of solid and liquid
particles formed during combustion of organic

16. (b) Dust is composed of fine solid particles,
produced
during crushing, grinding and attribution of solid
materials. Sand from sand blasting, saw dust from
wood works, cement and fly ash from factories etc.
(c) Mists are produced by particles of spray liquids
and
by condensation of vapours in air.
(d) Fumes are generally obtained by the
condensation of
vapours during sublimation, distillation, boiling and
several other chemical reactions.
• The effect of particulate pollutants are largely
dependent on the particle size. Air borne particles
are dangerous for human health.

17. •SMOG
•The word smog is derived from smoke and fog. This
is
the most common example of air pollution that
occurs
in many cities throughout the world. There are two
types
of smog:
(a) Classical smog occurs in cool humid climate. It is
the
mixture of smoke, fog and sulphur dioxide.
Chemically it is a reducing mixture and so it is also
called as reducing smog.
(b) Photochemical smog occurs in warm, dry and

18. •THE OZONE HOLE
• In 1980s atmospheric scientists in Antarctica
reported about the depletion of ozone layer. In
summer season, NO2 and methane react with
chlorine monoxide and chlorine atoms forming
chlorine sinks, preventing much ozone depletion. In
winter season a stratospheric cloud formed
providing surface on which chlorine nitrate and gets
hydrolyzed to form hypochlorous acid which reacts
with hydrogen chloride to form molecular chlorine.

19. EFFECTS OF DEPLETION OF OZONE LAY
• With the depletion of ozone layer, more UV
radiation
filters into the troposphere. UV radiations lead to
ageing of skin, cataract, sunburn, skin cancer,
killing of many phytoplanktons, damage to fish
productivity etc.
• The plant protein gets easily affected which leads
to
the harmful mutation of cells. Increase in UV
radiations damage paints and fibres, causing them
to fade faster.

20. •Water Pollution
•Water is essential for our life. Without water there
would be no life. Pollution of water originates from
human activities. Through different paths, pollution
reaches surface or ground water. Easily identified
source of pollution is called as point source. e.g..,
municipal and industrial discharge pipes where
pollutants enter the water-source.

21. •Causes of Water Pollution
(1)Pathogens: The most serious water pollutants are
the
disease causing agents called pathogens include
bacteria and other organisms that enter water from
domestic sewage and animal excreta.
(2)Organic wastes: The other major water pollutant
is
organic matter such as leaves, grass, trash etc.
Excessive phytoplankton's growth within water is
also
a cause of water pollution.
• A large population of bacteria decomposes organic
matter present in water. They consume oxygen
dissolved in water. The amount of oxygen that water

22. •Soil Pollution
Soil pollution or soil contamination is
caused by the presence of xenobiotic (human
made) chemicals or other alterations in the
natural soil and environment..
Causes :
 Waste Dumping
 Mining
Pesticides and Insecticides
Urbanization

23. WASTE DUMPING :
 Industrial solid wastes and sludge are the major sources of
soil pollution.
Industrial emissions such as fly ash from thermal power
plants can contaminate the surrounding soil.
 Nuclear testing laboratories and the increased number of
radioactive
nuclear reactions can contaminate the soil. Radioactive
materials are
thriving in the soil for long periods of time, since they often
have a long
half-life. Strontium-90, for example, a half life of 28 years, and
half-life
of cesium-137 is 30 years.

24. MINING :
 Modern mining projects leave behind disrupted
communities,
damaged landscapes, and polluted water.
 Mining also affects ground and surface waters, the aquatic
life, vegetation, soils, animals, and the human health.
 Acid mine drainage can cause damage to streams which in
return can kill aquatic life.
 The vast variety of toxic chemicals released by mining
activities can harm animals and aquatic life as well as their
habitat.
 Mining gas and petroleum also pollutes the land.
Petroleum
extraction and manufacturing contaminates the soil with
bitumen, gasoline, kerosene and mining brine solutions.
 Opencast mining, which is a process where the surface of
the

25. Pesticides :
 Many of the chemicals used in pesticides are
persistent soil contaminants, which adversely
affect soil conservation.
 The use of pesticides decreases the
general biodiversity in the soil.
 The insecticides DDT, methyl parathion and
especially pentachlorophenol have been
shown to interfere with legume-rhizobium
chemical signaling. Reduction of
this symbiotic chemical signaling results in
reduced nitrogen fixation and thus reduced
crop yields.
 Animals may be poisoned by pesticide
residues that remain on food after spraying,
for example when wild animals enter sprayed
fields or nearby areas shortly after spraying
 Widespread application of pesticides can
eliminate food sources that certain types of
animals need, causing the animals to
relocate, change their diet, or starve.
Poisoning from pesticides can travel up
the food chain and bioacculmulate.

26. STRATEGIES TO CONTROL
ENVIRONMENTAL DAMAGE :
The public is becoming increasingly aware
that the natural environment is fragile.
The recent reports by media have focused
on –
Deaths and population declines of birds and fish because
of the large oil spills.
 Deaths of porpoises and whales along the coasts as a
result of pollutants and disease.
 Fish contaminated with polychlorinated biphenyls (PCBs).
 Contamination of rivers and lakes by dioxin and other
pollutants that may cause cancer and reproductive disorders.

27. WASTE MANAGEMENT :
Waste management is the collection, transport, processing or
disposal, managing and monitoring of waste materials. The
term usually relates to materials produced by human activity,
and is generally undertaken to reduce their effect on health,
the environment or aesthetics. Waste management is a
distinct
practice from resource recovery which focuses on delaying
the
rate of consumption of natural resources. The management
of
wastes treats all materials as a single class whether solid,
liquid, gaseous or radioactive substances, and tried to
reduce
the harmful environmental impacts of each through different
methods.
The two major concepts which are widely used for waste

28. Methods Of Waste Management :
LANDFILL
Disposing of waste in a landfill involves burying the waste, and this remains a
common
practice in most countries. Landfills are often established in abandoned or
unused quarries, mining voids or borrow pits. A properly designed and well-
managed
landfill can be a hygienic and relatively inexpensive method of disposing of waste
materials. Older, poorly designed or poorly managed landfills can create a number
of
adverse environmental impacts such as wind-blown litter, attraction of vermin,
and
generation of liquid leachate.
Design characteristics of a modern landfill include methods to contain leachate
such as
clay or plastic lining material. Deposited waste is normally compacted to increase
its
density and stability, and covered to prevent attracting vermin. Many landfills also
have
landfill gas extraction systems installed to extract the landfill gas. Gas is pumped

29. AVOIDANCE & REDUCTION METHODS :
An important method of waste management is the prevention of waste
material being created, also known as waste reduction.
Methods of avoidance include :
-Reuse of second-hand products
-Repairing broken items instead of buying new
-Designing products to be refillable or reusable (such as cotton instead of
plastic shopping bags)
-Encouraging consumers to avoid using disposable products (such as
disposable cutlery)
-Removing any food/liquid remains from cans
-Designing products that use less material to achieve the same purpose
(for example, light weighting of beverage cans)