1. Sulphur dioxide and nitrogen oxides released from factories and vehicles react with water in clouds to form acid rain, which corrodes buildings and makes soils and lakes too acidic, killing fish and plants. 2. Acid rain is neutralized by adding calcium carbonate or hydroxide to affected lakes and soils. Flue gases from industries and power stations can be treated with calcium carbonate to remove sulphur dioxide before release. 3. The carbon cycle regulates the amount of carbon dioxide in the atmosphere through the processes of combustion, respiration and photosynthesis, which respectively produce, use and remove carbon dioxide from the air.

1. Objective
Discuss some of the effects of these pollutants on health and on the environment:
• the role of nitrogen dioxide and sulphur dioxide in the formation of ‘acid rain’ and its
effects on respiration and buildings.
KNOWING OUR RAIN!
Type of Pure Rainwater Acid
water water rain
pH 7 5.6 4

2. Objective
Discuss some of the effects of these pollutants on health and on the environment:
• the role of nitrogen dioxide and sulphur dioxide in the formation of ‘acid rain’ and its
effects on respiration and buildings.
1
2 and 3
4
houses
FACTORY
LAKE
5

3. Objective
Discuss some of the effects of these pollutants on health and on the environment:
• the role of nitrogen dioxide and sulphur dioxide in the formation of ‘acid rain’ and its
effects on respiration and buildings.
1
2 and 3
4
houses
FACTORY
LAKE
5
• Sulphur dioxide and nitrogen oxides gases are released into the air by
factories and vehicles.
The gases then react with air and water in the clouds to form ACID RAIN

4. Objective
Discuss some of the effects of these pollutants on health and on the environment:
• the role of nitrogen dioxide and sulphur dioxide in the formation of ‘acid rain’ and its
effects on respiration and buildings.
1
2 and 3
4
houses
FACTORY
LAKE
5
• Sulphur dioxide reacts with air and water to form sulphuric acid.
Chemical Equation:
2SO2 + O2 + 2H2O  2H2SO4
3. Nitrogen dioxide reacts with air and water to form nitric acid.
Chemical Equation:
4NO2 + O2 + 2H2O  4HNO3

5. Objective
Discuss some of the effects of these pollutants on health and on the environment:
• the role of nitrogen dioxide and sulphur dioxide in the formation of ‘acid rain’ and its
effects on respiration and buildings.
1
2 and 3
4
houses
FACTORY
LAKE
5
4. The acid rain corrodes limestone buildings and metal structures.
5. Soils and lakes become too acidic.
Acid rain kills fish.
Acid rain leaches nutrients from soils and destroys plants.

6. Objective
Discuss some of the effects of these pollutants on health and on the environment:
• the role of nitrogen dioxide and sulphur dioxide in the formation of ‘acid rain’ and its
effects on respiration and buildings.
Sulphur dioxide and nitrogen
oxides also cause irritation of the
eyes
and breathing difficulties by
irritating the lungs

7. Objective
Describe the reactions used in possible solutions to the problems arising from some of the
pollutants
• the use of calcium carbonate to reduce the effect of acid rain
Cure for ACID RAIN!
The lakes contaminated by acid rain
can be neutralised by calcium
hydroxide (limewater) or
calcium carbonate (limestone).

8. Objective
Describe the reactions used in possible solutions to the problems arising from some of the
pollutants
• flue gas desulphurisation
Prevention of ACID RAIN
Prevention is absolutely better than cure. But how do we make
it possible?
• removing sulphur dioxide from waste gases (from
industries and power stations) before they are released
into the air known as flue gas desulfurisation.
Sulphur dioxide is removed by reacting with
calcium carbonate (or calcium oxide) to form
calcium sulphite.
CaCO3 (s) + SO2 (g) CaSO3 (s) + CO2 (g)
The calcium sulphite is further oxidised to form
calcium sulphate.
2CaSO3(s) + O2 (g)  2CaSO4 (s)

9. Objective
Describe the reactions used in possible solutions to the problems arising from some of the
pollutants
• the redox reactions in catalytic converters to remove combustion pollutants.
Removal pollutants such as carbon monoxide and
nitrogen oxides from car exhaust
This can be done by installing a catalytic converter
in the vehicles
CO2 + N2 When the exhaust gases pass over
the catalyst in the converter, a redox
reaction occurs and the harmful
Catalytic pollutants are changed into harmless
gases.
Converter
The carbon monoxide is oxidised to
carbon dioxide and oxides of nitrogen
reduced to nitrogen gas
CO + NO
2NO(g) + 2CO (g)  N2 (g) + 2CO2 (g)

10. Objective: Discuss the importance of ozone layer and the problems involved
with the depletion of ozone by reaction with chlorine containing compounds,
chlorofluorocarbon, (CFCs)
Importance of OZONE LAYER
Ozone is an element with molecular formula O3. The ozone layer in the
atmosphere acts as a shield to filter out the harmful uv radiation from the
sun.
SUN Ozone layer filters out harmful
uv light
If this harmful uv radiation is allowed to reach the surface of the
earth, there would be an increase in
• skin cancer
• eye damage e.g. cataract
• genetic mutation

11. Objective: Discuss the importance of ozone layer and the problems involved
with the depletion of ozone by reaction with chlorine containing compounds,
chlorofluorocarbon, (CFCs)
What causes the depletion of ozone layer in
the atmosphere?
Chlorofluorocarbons
CFCs

12. Objective: Discuss the importance of ozone layer and the problems involved
with the depletion of ozone by reaction with chlorine containing compounds,
chlorofluorocarbon, (CFCs)
3 In the presence of
sunlight, CFCs decompose
to form chlorine atoms
2
CFCs reach the
atmosphere where the
ozone layer is found
4 Chlorine atoms react with ozone molecules
in the ozone layer to
form chlorine oxide
5 and oxygen, thus
Ozone layer is destroying the ozone
destroyed layer
1
Propellent from
aerosols release 6
CFCs into the Harmful uv light reaches
atmosphere earth through the holes in
the ozone layer

13. Objective: Describes the carbon cycle in simple terms, to include combustion,
respiration and photosynthesis
What is the carbon cycle?
The mechanisms that maintain the level
of carbon dioxide in the atmosphere

14. Objective: Describes the carbon cycle in simple terms , to include combustion,
respiration and photosynthesis and how carbon cycle regulates the amount of
CO2 in the atmosphere
3 main processes in the carbon cycle that maintains the level of carbon
dioxide in the air are:
Atmospheric carbon  Combustion of fuel
dioxide Carbon dioxide
is produced
 Respiration
 Photosynthesis
Carbon dioxide is removed.
During photosynthesis, green plants
convert carbon dioxide and water into
Carbon dioxide is produced. food (glucose) and oxygen in the
It is a process in which food presence of sunlight
taken in by living things are 6CO2 + 6H2O  C6H12O6 + 6O2
converted into carbon dioxide glucose
and water
C6H12O6 + 6O2 6CO2 + 6H2O

15. Objective: State that carbon dioxide and methane are greenhouse gases and
may contribute to global warming
Some radiation
escapes into
space Some radiation absorbs
by the gases in the
Solar radiation atmosphere atmosphere
They are called
greenhouse gases.
Examples : carbon dioxide
& methane
The earth’s surface is heated by radiation from the sun.
Some gases in the air trap this heat radiation and prevent
much of it from escaping into space. The energy retained in
the atmosphere produces a warming effect known as the
greenhouse effect. This leads to an increase in the earth’s
temperature or global warming.
Is the greenhouse effect important?
Yes, without the greenhouse gases, the earth would
be too cold for life to exist. It is the excessive
greenhouse gases that leads to global warming

16. Objective: State that carbon dioxide and methane are greenhouse gases and
may contribute to global warming, give the sources of these gases
Reasons for increase in CO2 and methane in the atmosphere
Deforestation – when trees grow, they absorb carbon dioxide
during photosynthesis. If there are less trees, more carbon dioxide
will remain in the atmosphere. In addition, when trees are burnt,
carbon dioxide is also given off.
Burning of carbon containing fuel in
factories.
Bacteria decay of vegetation and
wastes produce methane gas

17. Objective: State that carbon dioxide and methane are greenhouse gases and
and discuss the possible consequences of an increase in global warming
Effects of increase in Global warming
 a decrease in crop yield worldwide. Areas covered by
vegetation may become deserts.
melting of ice in the North and South Poles. Low lying
countries will be flooded.
rapid evaporation of water from the earth
surface. When this happen, carbon dioxide
dissolved in the ocean will be driven out into the
atmosphere.