Here are the key ways to control water pollution mentioned on page 41: - Treat domestic and industrial waste before discharging into water sources. This involves processes like sedimentation, filtration and disinfection. - Control surface runoff from agricultural land by terracing, contour ploughing and establishing buffer zones along water bodies. This prevents soil erosion and entry of agricultural chemicals into water. - Proper disposal of solid waste and control of open defecation to prevent entry of pathogens into water sources. - Control discharge of oil and chemical spills from ships and tankers. - Maintain minimum flow in rivers to ensure sufficient self-purifying capacity. Abstraction of water should be regulated. -

1. Chapter 5
Water and Solution

2. Water is the most abundant substance on
earth.
Like any other substances, water has its own
unique characteristics.

3. 5.1 Physical Characteristics of Water
A. Physical Characteristics of Water
1. Water can exist in three states:
a. Solid b. Liquid c. Gas

4. 5.1 Physical Characteristics of Water
2. At room temperature, pure water is a
a. colourless,
b. odourless and
c. tasteless.

5. 5.1 Physical Characteristics of Water
Freezing Point of Water
1.Water changes from liquid to solid at its freezing
point.
liquid solid
Freezing point of water is the temperature at
which water freezes into ice.

6. 5.1 Physical Characteristics of Water
2. The freezing point of pure water is 0 oC.
3. The temperature remains constant at 0 oC until water
freezes completely.

7. 5.1 Physical Characteristics of Water
When the temperature drops, the water
particles move slower.
Therefore, the forces of attraction among the
particles grow stronger.
At 0 oC, the forces of attraction are so great
that the water particles are held in fixed
positions.
Waterfreezes into ice!

8. 5.1 Physical Characteristics of Water
Boiling Point of Water
1. Water boils at its boiling point.
liquid gases
Boiling point of water is the temperature at
which water boils and becomes steam.

9. 5.1 Physical Characteristics of Water
2. The boiling point of pure water is 100 oC.
3. The temperature remains constant at 100 oC until
water boils completely.

10. 5.1 Physical Characteristics of Water
When the temperature rises, the water particles
move faster and further apart.
Therefore, the forces of attraction among the
particles grow weaker.
At 100 oC, water particles move so fast that
they overcome the forces of attraction and
leave the liquid’s surface.
Waterbecomessteam!

11. 5.1 Physical Characteristics of Water
5. Water conducts heat slowly. Water is a poor
thermal conductor.
6. Water is also a poor electrical conductor.
7. The density of water varies with temperature.
Pure water has the maximum density of 1 g
per cm3 at 4 oC.

12. 5.1 Physical Characteristics of Water
B. Effects of Impurities on the Physical
Characteristics of Water
1. Impurities in water can change the
physical characteristics of water. Sometimes
the change is noticeable and sometimes it is not.

13. 5.1 Physical Characteristics of Water
2. Here are some examples:
Physical Example
characteristic
Taste Purewateristastelessbutseawaterissalty.
Odour Purewaterisodourless.Waterwithdecayedmatterhasanunpleasant
smell.
Colour Purewateriscolourlessbutmuddywaterisbrownishincolour.
Density Purewaterislessdensethanseawater.
Electricalconductivity Purewaterwithafewdropsofsulphuricacidcanconductelectricity.
Freezingpoint o
Purewaterfreezesat0Cbutseawaterfreezesatalower
temperature.
Boilingpoint o
Purewaterboilsat100Cbutseawaterboilsatahighertemperature.

14. 5.2 Composition of Water
Composition of Water
1. Water is a compound. It is made of two different
elements.
Water
Hydrogen Oxygen

15. 5.2 Composition of Water
2. Water can be broken down to its elements
through electrolysis.
A method to break down a compound by passing
an electric current through its liquid or solution

16. 5.2 Composition of Water
3. The volume of hydrogen released is always
twice the volume of oxygen released.
Oxygen is Hydrogen is
released at the released at the
anode cathode

17. 5.2 Composition of Water
4. Water is made up of one part of oxygen and two parts of
hydrogen.
Oxygen atom
Hydrogen atoms
Each water molecule consists of one atom of oxygen and
two atoms of hydrogen.

18. 5.2 Composition of Water
5. Therefore, scientists represent water with the
following formula:
H2O
H – Represents the hydrogen atom
2 – Shows that there are two atoms of hydrogen
O – Represents the oxygen atom

19. Applying the principle of water evaporation
In our daily life.
1. To drying clothes
2. To drying hair
3. To drying agricultural produce
4. To drying fish and prawn
5. To cooling the body
6. To producing the common salt

20. 5.4 Solution and Solubility
Solution and Solubility

21. 5.4 Solution and Solubility
1. What is a solution?
• A solute is the
substance that dissolves.
• A solvent is the
substance that the solute
dissolves in.

22. 5.4 Solution and Solubility
2. Depending on the amount of solutes in
solutions, there are three types of solutions.
Solution
Dilute solution Concentrated solution Saturated solution
Contains a little Contains a lot of Contains the maximum
dissolved solute dissolved solute amount of dissolved solute
Can dissolve a lot Can dissolve a little bit Cannot dissolve any more
more solute more solute solute
All these solutions have a clear appearance

23. 5.4 Solution and Solubility
1. What is a suspension?
A suspension is a mixture containing insoluble
substances.
2. There are many suspensions around us.
Muddy water, fruit juices, chocolate drink, blood

24. 5.4 Solution and Solubility
1. What is ‘solubility’?
The solubility of a solute is the maximum amount of solute in
grams that will dissolve in 100 g of solvent at a given
temperature.
For example, the solubility of sodium chloride is 38 g per 100
g of water at 20 oC.
This means that you can dissolve not more than 38 g of sodium
chloride in 100 g of water at 20 oC.

25. 5.4 Solution and Solubility
2. Factors Affecting the Solubility of a Solute
a. The nature of the solvent
b. The nature of the solute
c. The temperature of the solvent

26. 5.4 Solution and Solubility
i. The nature of the solvent
- The solubility of a solute differs in
different solvents.
Example:
Only a little iodine can dissolve in water. Iodine can
dissolve very well in alcohol.

27. 5.4 Solution and Solubility
ii. The nature of the solute
Different solutes have different solubility
in the same solvent.
Example:
At the same temperature, sodium chloride has a
lower solubility in water compared to copper chloride.

28. 5.4 Solution and Solubility
1. What are the factors affecting the rate
of dissolving a solute?
a. Temperature
b. Rate of stirring
c. Size of solute particles

29. 5.4 Solution and Solubility
i. Temperature
The higher the temperature of the solvent, the higher the
rate of dissolving.
:
We use hot water to make
tea. One reason for this is
that hot water increases
the rate of dissolving of
certain substances in the
tea leaves.

30. 5.4 Solution and Solubility
ii. Rate of stirring
The higher the rate of stirring, the higher the rate of
dissolving.
:
The faster you stir the
soup, the faster the salt
dissolves in it.

31. 5.4 Solution and Solubility
iii. Size of solute particles
The smaller the size of the solute particles, the higher the
rate of dissolving.
Smaller pieces of palm
sugar can dissolve in water
faster than a big piece of
it.

32. 5.4 Solution and Solubility
Water is a good solvent. Almost everything can dissolve in it to
produce solutions. Therefore, water is also known as the
universal solvent.
Water acts as a medium in many chemical reactions in
our body.
Water dissolves and transports many substances in our
body such as digested food and waste products.
Water dissolves cleaning agents such as soap powder,
dishwasher liquid and toilet cleaner.

33. 5.4 Solution and Solubility
Water dissolves various substances. This enables us to
use water in cooking and making drinks.
Water is used extensively in food industry as a solvent.
Water is used to prepare traditional and modern liquid
medicines.
Farmers use water to dissolve pesticides.
Water is needed in plants to transport food and
dissolved minerals.

34. 5.4 Solution and Solubility
Some substances cannot dissolve in water but they can
dissolve in organic solvents.
What are organic solvents?
Organic solvents are carbon compounds that are used
as solvents.
Examples:
• Alcohol • Turpentine • Acetone

35. 5.4 Solution and Solubility
1. We use many organic solvents in various products.
To produce lacquers and varnishes
To produce various types of ink
Alcohol
To prepare iodine solution (as an antiseptic)
To produce perfume
To produce paints
Turpentine
To remove paint stains
To produce nail polish
Acetone
To remove nail polish

36. 5.4 Solution and Solubility
2. Organic solvents are very useful to us.
a. They are volatile. Therefore, products such as
paints, lacquers, varnishes and inks become dry in a
short period of time.
b. They can dissolve many solutes that do not dissolve
in water.
3. However, products containing organic solvents
should be handled carefully.
a. They are flammable and should be stored away
from heat.
b. They are toxic and carcinogenic (likely to cause
cancer).

37. 1. An acid is a substance that has a hydrogen
atom, which can be replaced by a metal
or ammonium.
2. Acid can be divided into two groups and
differences are shown below

38. ACID
Organic acid Inorganic acid
Example
Acetic acid
Example
Formic acid
Sulphuric acid
Lactic acid
Nitric acid
Malic acid
Hydrochloric acid
Citric acid
Carbonic acid
Tannic acid
Tartaric acid

39. 3.An acid exist in three state which are
a. solid – tartaric acid
b. liquid – ethanoic acid
c. gas – hydrogen chloric
4. The properties of acids
a. Taste sour
b. Are corrosive
c. Change blue litmus paper to red
d. Have pH values of less than 7
e. React with carbonates to release carbon dioxide
and form salt and water
acid + cabonates salt + water + carbon dioxide

40. f. React with active metals to release hydrogen and form
salt.
acid + metal salt + hydrogen
g. React with alkalis to form salt and water
acid + alkali salt + water

41. 1. An alkalis is hydroxide or metal oxide that
dissolves in water.
2. Example: potassium hydroxide, sodium
hydroxide, calcium hydroxide, ammonium
hydroxide solutions.

42. 12 3 4 5 6 7 8 9 10 11 12 13 14
Acidity increases Alkalinity increases
neutral

43. 5.5 Acid and Alkali
Neutralisation
Neutralization is a process where
acid + alkali  salt + water
Note: Where acid reacts with alkali, salt and water are formed.
Different kinds of acids and alkalis will form different types of salt.

44. 5.6 Water Purification
Natural Sources of Water
Natural Sources of Water
From Ocean From lakes, streams,
rivers, ground water
•Salty (well) and rain
• Not suitable for
human consumption • Fresh Water
• But not pure, need to be purified

45. a. Most pure
b. Has very little dissolved substances and a
little dust

46. a. Not clean
b. Has a lot of dissolved substances and dirt
such as microorganisms and silt

47. a. Has microorganisms and dissolved
substances
b. Cleaner than river

48. a. Has the most substances of salt
b. Has the most of dirt.

49. 5.7 Water Supply System
Usage of Water
Usage of Water
Domestic Use Agricultural Use Direct Use of Industrial Use
of Water of Water Rivers and of Water
Streams
• Drinking
• Irrigation • Cooling
• Washing • Generate
• Aquaculture • Washing
• Watering
Hydroelectric
Plants • Disposal
Power
of Waste
• Recreation
• Transportation

50. METHOD OF PURIFICATION
Chlorination
Chlorine solution

51. Filtration
Muddy water
Fine sand
Coarse sand
Pebbles
Gravel
filtrate

52. Boiling
filtrate

53. Distillation
Water
out
Liebig
condenser
Muddy
Water
Water in
Distilled
water

54. 1. Water from natural sources have various
impurities such as microorganisms, dissolved gases,
mineral salts and silt.
2. Water from natural sources must be purified so that it
save to drink and use.
3. Table shows the advantage and disadvantage of
water purification.

55. Waterpurificationmethod advantage disadvantage
a. Filtration Waterisclear Waterstillhas
Onlyremoves andfree microorganisms
impuritiesthatare suspended anddissolved
coarsesuchas particlesonly substances
suspendedsubstances. (suchas
Sandfiltersare mineralsalts)
commonlyused

56. b. Distillation  Water is free 
Water does
 Prepares pure or from all not make
distilled water suspended good
substances, drinking
microorganisms because it
and dissolved does not
substances. contain
dissolved
mineral
with our
body need.

57. c. Boiling and
chlorination  Water is free from  Water still has
 Only kills dangerous dissolved
microorganisms in microorganisms substances and
water suspended
substances.

58. WATER TREATMENT PLANT
1. Refer to your text book pg. 36 and draw figure 5.34
PRESERVATION OF WATER QUALITY
1. Find out the ways to control water pollution on page 41.