Acid rain is caused by sulfur dioxide and nitrogen oxides emissions from the burning of fossil fuels. These gases mix with water vapor and rainwater to produce acids like sulfuric acid and nitric acid, lowering the pH of the rainwater. Acid rain damages the environment by speeding up the weathering of rocks and buildings, making soils and waters too acidic for plants and animals to survive, and damaging trees. Governments are working to reduce emissions and require industry to install pollution control technologies to reduce the production of acid rain.

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MILE STONE ACADEMYMILE STONE ACADEMY

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CONTANT
Causes
Contents
PROBLEM
ACID AFFECTS
THE SOIL
LAKES

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Causes of Acid Rain
• Burning coal. Oil and natural
gas in power stations makes
electricity, giving off sulphur
dioxide gas.
• Burning petrol and oil in
vehicle engines gives off
nitrogen oxides as gases.
• These gases mix with water
vapour and rainwater in the
atmosphere producing weak
solutions of sulphuric and
nitric acids – which fall as
acid rain.

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What is acid rain?
Normal rainwater has a pH of about 5.6,
which means it is naturally slightly acidic.
This natural acidity is due to carbon
dioxide which dissolves in rainwater
and forms carbonic acid, a weak acid.
Rainwater with a lower pH than normal is called acid rain.
The burning of fossil fuels in power
stations and cars forms pollutants such
as sulfur dioxide and nitrogen oxides.
These gases dissolve in rainwater to
make sulfuric and nitric acids, which
are strong acids and so form acid rain.
Why is acid rain a serious environmental problem?

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Acid rain animation

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Effects of acid rain
Acid rain has many damaging effects on the environment:
The strong acids in acid rain
speed up the chemical weathering
of rocks and buildings.
Rivers, lakes and streams become
more acidic so that animals and
plants cannot live in them.
Soil that becomes more acidic has
les nutrients so trees and other
plants cannot grow. Acid rain also
damages trees by breaking down
the waxy coating of leaves.
What can be done to reduce acid rain and its effects?

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Reducing acid rain
Governments are working to reduce the emission of acidic
pollutants caused by burning fossil fuels.
Sulfur dioxide is formed when coal
containing sulfur is burned in power
stations.
This acidic pollutant can be removed
from the gases that are released to
the atmosphere.
Nitrogen oxides are formed when
petrol burns in vehicle engines.
A car’s exhaust system can be fitted
with a catalytic converter which turns
harmful gases into harmless gases.
How do these changes help to reduce acid rain?

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The Problem!
People probably couldn't live without
electricity! Therefore coal will continue to be burnt.
Also, electricity and energy are constantly
being overused.
Think of it this way: every time you turn on a
light switch or the television set without really
needing to, you're indirectly contributing to the acid
rain problem.

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More problems!!!
• Acid rain can travel long distances.
• Often it doesn’t fall where the gas is
produced. High chimneys disperse
(spread) the gases and winds blow
them great distances before they
dissolve and fall to Earth as rain.
• Eg gases produced in England and
Western Europe can result in acid
rain in Scotland and Scandinavia.

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How Acid Rain Affects The
Environment
Acid rain is an extremely destructive
form of pollution, and the
environment suffers from its effects.
Forests, trees, lakes, animals, and
plants suffer from acid rain.
Trees
The needles and leaves of the trees
turn brown and fall off.
Trees can also suffer from stunted
growth; and have damaged bark
and leaves, which makes them
vulnerable to weather, disease, and
insects.

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The soil
All of this happens partly
because of direct contact
between trees and acid rain,
but it also happens when
trees absorb soil that has
come into contact with acid
rain.
The soil poisons the tree
with toxic substances that
the rain has deposited into
it.

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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, or acid deposition, is a
mixture of sulphuric and nitric
acids.
• Wet deposition
– rain
– hail
– snow
– fog
• Dry deposition gases
and particles

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a) Acid reactions with sulphur
S + O2 → SO2
2SO2 + O2 →2SO3
2-
SO3
2-
+ H2 O → H2SO4
b) Acid reactions with nitrogen
N2 +O2 →2NO
2NO +O2 →2NO2
4NO2+O2 + 2H2 O →4 HNO3
Causes and chemistry

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NATURAL:

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