GREENHOUSE GASES AND WATER TREATMENT NOTES.ppt

IGCSE CHEMISTRY

1. The Greenhouse Effect and
Global Warming

3. Heat from the sun shines
onto the Earth.
It passes through a
blanket of gases in
our atmosphere.

4. Some of the heat
energy is reflected
back into space.
Some of the heat energy
is absorbed by the
blanket of gases.

5. The ‘greenhouse’ gases are
essential to life on Earth. Without
them heat energy would escape
back into space.
Earth would be a
very chilly place
with an average
temperature of
-18°C !

6. The gases work a bit
like glass in a
greenhouse to trap in
warmth.
But the earth is
getting warmer and
warmer.
WHY?
The greenhouse gases help to keep
the temperature of the earth in
balance. This process is called the
GREENHOUSE EFFECT.

7. Human activities are creating
more greenhouse gases
including carbon dioxide, CO
2.
As we burn more
fossil fuels, for
example, the
blanket of
greenhouse gases
becomes thicker.

8. More greenhouse gases in the
atmosphere mean that more
heat energy is absorbed.
We call this increase
in the temperature
of the earth
‘global warming’.

9. What are Greenhouse gases?
•Carbon Dioxide (CO
2)
•Methane (CH
4
)
–Cows and other animals
–Decomposing garbage

10. Is the Greenhouse Effect Bad?
•Without the greenhouse effect the earth
would be cold as Mars!
•But too much Greenhouse gas can heat up the Earth too fast
–Rising seas
–Polar ice melting
–Unpredictable storms

11. What can we do to prevent global
warming?
•Use sources of energy that do not emit
carbon dioxide (CO
2)
–Solar, Hydrogen, Wind, Biodiesel
•Reduce the amount of energy we use
–Cars with better gas mileage
–Energy-efficient appliances
–Turning off electrical appliances when not in
use.

12. What are we doing today?
+
= CO
2

13. Water
By Jacob Tito

14. Learning Objectives
Describe, in outline, the treatment of the water supply
in terms of filtration and chlorination
Name some of the uses of water in industry and in the
home
Discuss the implications of an inadequate supply of
water, limited to safe water for drinking and water for
irrigating crops
Describe chemical tests for water using
cobalt(II)chloride and copper(II) sulfate

15. Key words
Filtration
chlorination

16. Home work
What are the effects of inadequate water
supply?

17. Water treatment
Untreated water contains soluble and insoluble impurities
Insoluble impurities include soil, plastics and pieces of plants.
Soluble impurities include dissolved calcium, metallic compounds and
inorganic pollutants
Filtration is the process used to remove large insoluble particles by
passing the water through layers of sand and gravel filters that trap larger
particles
But bacteria and other microorganisms are too small to be trapped by the
filters so chlorination is used
This involves the careful addition of chlorine to the water supply which
kills bacteria and other unwanted microorganisms
Cholera and typhoid are examples of bacterial diseases which can arise
by the consumption of untreated water

19. Uses of water in industry
As a coolant to reduce the temperature of some
industrial processes
Watering crops
As a solvent in many chemical production processes
Hydroelectric power stations to generate electricity
As a raw material for many processes e.g: the
production of ethanol from ethene and steam (water)

20. Use of water in homes
Drinking, cooking and washing
General sanitation.
In car radiators
For gardens and plants

21. Chemical tests for water
Cobalt (II) chloride paper turns from blue
to pink on the addition of water.
Anhydrous copper (II) sulfate turns from
white to blue on the addition of water