Acid rain is rain with a pH lower than 5.6 due to acidifying pollutants like sulfur and nitrogen oxides from fossil fuel combustion and other industrial processes. It forms when these gases dissolve or react with moisture in the atmosphere to produce acids. Acid rain damages ecosystems, infrastructure, and human health. It harms plants, aquatic animals, and soils. Solutions include reducing air pollution through cleaner energy and transport, and adding limestone to neutralize acidity.

1. Objectives:
• What is Acid Rain?
• How the Acid rain gets formed?
• What are the constituents of Acid rain?
• What are the causes of Acid rain?
• What are the effects of Acid rain?
• Solution to Acid rain.

3. Acidity of Water and Acid rain:
• Water having PH (Power of Hydrogen) >7 is
termed as alkaline water.
• Water having PH =7 is termed as Normal
water.
• Water having PH <7 and more than 5.6 is
termed as normal rain.
• Water having PH <5.6 is termed as Acid
rain.

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• As said before that acid rain is rain having
PH<5.6 but not 7, this is because that the
normal rain naturally contain slight acid i.e.
when the rain comes to earth it dissolves
CO2 from the atmosphere to form weak
carbonic acid and thus having PH=5.6, now
if the acidity decreases from 5.6, the rain is
said to be Acid rain.
Acidity increases by:
1 in PH=10 times in acidity

5. Figure_1: PH scale of water

6. Constituents of Acid rain:
The following are the main constituents of
Acid rain
• Sulfuric Acid (H2SO4)
• Nitric Acid (HNO3)
• Carbonic Acid (CO2)

7. Formation of Acid rain:

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• Plants need a little Sulphur to grow, they
obtain it from sulfates such as K2SO4, the
sulphur is bound with carbon in plants’
leaves, the plants are converted into fuel in
appropriate conditions after it dies, now if
the fuel is burnt the sulphur and carbon
reacts with O2 and form SO2 ,CO2, the
presence of sunlight SO2 reacts with more
O2 and for SO3 which finally reacts with rain
water and forms H2SO4.

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• N2 and O2 react in the engine of automobile
to form NO2, as the NO2 is released in the air
it reacts with more O2 in the presence of
sunlight and forms NO3 which then
dissolves with water and form Nitric Acid
HNO3.

10. Figure_2: Formation of Acid rain

11. Acid rain depositions:

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14. Causes of Acid rain

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There are two types of causes of Acid rain:
• Natural causes
• Artificial causes
The natural causes contains fogs, volcanic
eruption, forest fire and lightning.

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Artificial causes of Acid rain:
• Burning of fossil fuel in industries, factories,
homes which produces NO2 which helps in
forming of Nitric Acid.
• Burning of petrol and diesel in automobile
engine which produces SO2, which helps in
forming of Sulphuric Acid.
• Burning of wood and natural gases which
produces CO2, and aerosol.

17. Adverse effects of Acid rain:

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Acid rain dissolves the stonework and mortar
of buildings (especially those made out of
sandstone or limestone).
It reacts with the minerals in the stone to form
a powdery substance that can be washed away
by rain.

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Currently, both the railway industry and the
aeroplane industry are having to spend a lot of
money to repair the corrosive damage done by
acid rain. Also, bridges have collapsed in the
past due to acid rain corrosion.

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• Humans can become seriously ill, and can even
die from the effects of acid rain. One of the
major problems that acid rain can cause in a
human being is respiratory problems.
• Many can find it difficult to breathe, especially
people who have asthma. Asthma, along with
dry coughs, headaches, and throat irritations
can be caused by the sulphur dioxides and
nitrogen oxides from acid rain.

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• Lakes are also damaged by acid rain. Fish
die off, and that removes the main source of
food for birds. Acid rain can even kill fish
before they are born when the eggs are laid
and come into contact with the acid.
• Fish usually die only when the acid level of a
lake is high; when the acid level is lower,
they can become sick, suffer stunted growth,
or lose their ability to reproduce.
• Also, birds can die from eating "toxic" fish
and insects.

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Acid rain can be absorbed by both plants
(through soil and/or direct contact) and
animals (from things they eat and/or direct
contact). When humans eat these plants or
animals, the toxins inside of their meals can
affect them. Brain damage, kidney problems,
and Alzheimer's disease has been linked to
people eating "toxic" animals/plants.

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28. What are
the
solutions
to acid
rain?

29. Solutions to Acid rain:

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• Powdered limestone/limewater added to
water and soil to neutralize acid.
• we can lower the pollution by using public
transport
• we can make an effort to save energy by
switching off lights when they are not being
used (when less electricity is being used
pollution from power plants decreases)
• Use renewable energy like wind power, solar
panels, tidal power, HEP schemes and
geothermal energy.

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33. References:
• Environmental Studies by B. R. Shah &
Snehal Popapli 8th edition 2015
• https://en.wikipedia.org/wiki/Main_Page
• https://www.youtube.com/watch?v=Nf8cu
vl62Vc&t=84s
• https://www.slideshare.net