1.Physical characteristics of water.
(a) Water can exist in three states of matter when receives or loses heat.
Ice → Water → Steam
(b) The density of pure water is 1 g per cm3.
(c) A weak heat conductor
(d) The freezing point is 0°C.
(e) The boiling point is 100°C.
(f) A colorless, tasteless and odourless liquid at room temperature.
2.Composition of water:
(a) Ratio of hydrogen molecule to oxygen molecule; 2:1.
3.Water expand upon freezing
4. Test for presence of water
(a) Anhydrous copper sulphate changes color from white to blue.
(b) Cobalt chloride paper changes color from blue to pink.
Aim:
To study the composition of water through the process of electrolysis
Method:
1. A few drops of dilute sulphuric acid is added to the distilled water.
2. The circuit is switched on end the electrical current is allowed to flow for 15 minutes.
3. The volume of the gases collected in cathode measuring cylinders and anode measuring cylinders are recorded.
4. The electrical current is allowed to flow until both measuring cylinders are filled with gas.
5.The gases in measuring cylinders anode and cathode are tested with a glowing wood splint and a burning wood splint respectively.
6.Gas collected at the cathode burns with a 'pop' sound when tested with a lighted splinter (a positive test for the presence of hydrogen). This means that hydrogen is discharged at the cathode.
7.The ratio of volume of gases produced in anode to that of the cathode is 1:2.If the volume of oxygen collected is 10cm³ , the volume of hydrogen collected is 20cm³.
(c) A weak heat conductor
(d) The freezing point is 0°C.
(e) The boiling point is 100°C.
(f) A colorless, tasteless and odourless liquid at room temperature.
2.Composition of water:
(a) Ratio of hydrogen molecule to oxygen molecule; 2:1.
3.Water expand upon freezing
4. Test for presence of water
(a) Anhydrous copper sulphate changes color from white to blue.
(b) Cobalt chloride paper changes color from blue to pink.
5.Impurities will affect the boiling point and freezing point of water. Water with impurities will
(a) Boil at a temperature above 100°C.
(b) Freeze at a temperature below 0°C.
6.Scientists represent water with the formula H2O (H stands for Hydrogen and O stands for Oxygen)
7.The composition of water can be determined by a process called elctrolysis.
8. Electrolysis of water is the breaking down of water into its elements by passing an electric current through it.
9.
To study the composition of water through the process of electrolysis
Method:
1. A few drops of dilute sulphuric acid is added to the distilled water.
2. The circuit is switched on end the electrical current is allowed to flow for 15 minutes.
3. The volume of the gases collected in cathode measuring cylinders and anode measuring cylinders are recorded.
4. The electrical current is allowed to flow until both measuring cylinders are filled with gas.
5.The gases in measuring cylinders anode and cathode are tested with a glowing wood splint and a burning wood splint respectively.
6.Gas collected at the cathode burns with a 'pop' sound when tested with a lighted splinter (a positive test for the presence of hydrogen). This means that hydrogen is discharged at the cathode.
7.The ratio of volume of gases produced in anode to that of the cathode is 1:2.If the volume of oxygen collected is 10cm³ , the volume of hydrogen collected is 20cm³.
Conclusion:
- Water is a chemical compound that consists of two parts hydrogen and one part oxygen
- The symbols for hydrogen and oxygen are H and O respectively. The symbol for one molecule of water is H2O.
- The positive electrode is known as the anode while the negative electrode is the cathode.
- Oxygen is collected at the positive electrode (anode) in measuring cylinder X whereas hydrogen is collected at the negative electrode (cathode) in measuring cylinder Y.
- The ratio of hydrogen to oxygen collected 2:1 . Therefore, the ratio of hydrogen to oxygen in one water molecule is 2:1.
- Water is a weak conductor of electricity. Therefore, a few drops of sulphuric acid are added to it so that it can conduct electricity better.
H20(water) ----->(electrolysis) 2 hydrogen atoms + oxygen
10. Evaporation of Water
a). the surface of the liquid,
b). the temperature below boiling point of the liquid.
1.Surface area of water
- The rate of evaporation increases when the surface area of water increases.
2.Humidity of the air
- Water evaporates faster when the humidity is lower.
3.Movement of air
- The rate of evaporation increases when there is movement of air.
4.Temperature of the surroundings
- The rate of evaporation increases when the temperature increases.
Similarities of Evaporation and Boiling
- Process by which a liquid changes into vapour.
- Heat energy is absorbed.
Application of evaporation in daily life.
1. To obtain salt from sea water
2. To dry products from agriculture such as cocoa, pepper, tea leaves and paddy.
3. To dry clothes
4. To process milk powder
5.4 Solution and solubility
a) A solution is produced by dissolving a solute in a solvent.
b) Solvent (Water) + Solute (Sugar) = Solution ( Sugar solution)
(Liquid that dissolves ( A substances that is ( A mixture of the solute and
a substance) dissolved) the solvent)
c) A dilute solution is a solution that contains very little solute.
d) A concentrated solution is a solution that contains a lot of solute.
e) A saturated solution is a solution that contains the maximum amount solute and cannot be dissolved any more at the given temperature.
f) A solution is homogeneous. There is a uniform distribution of solvent and solute through out the solution.
g) A suspension is a cloudy mixture containing insoluble sediments (tiny particles of solid matter floating in it which will eventually settle to the bottom).
h)The solubility of a substances is
i) the maximum mass of the substances(solute) that can dissolve in 100 cm³ of the solvent at a specific temperature.
ii) varies with temperature
i)Definition of solubility of a substances- The maximum quantity of solute that can dissolve in 100g solvent at certain temperature.
10. Evaporation of Water
a). the surface of the liquid,
b). the temperature below boiling point of the liquid.
Factors affecting the rate of evaporation of water
- The rate of evaporation increases when the surface area of water increases.
2.Humidity of the air
- Water evaporates faster when the humidity is lower.
3.Movement of air
- The rate of evaporation increases when there is movement of air.
4.Temperature of the surroundings
- The rate of evaporation increases when the temperature increases.
Similarities of Evaporation and Boiling
- Process by which a liquid changes into vapour.
- Heat energy is absorbed.
 |
| The differences between evaporation and boiling |
1. To obtain salt from sea water
2. To dry products from agriculture such as cocoa, pepper, tea leaves and paddy.
3. To dry clothes
4. To process milk powder
5.4 Solution and solubility
a) A solution is produced by dissolving a solute in a solvent.
b) Solvent (Water) + Solute (Sugar) = Solution ( Sugar solution)
(Liquid that dissolves ( A substances that is ( A mixture of the solute and
a substance) dissolved) the solvent)
c) A dilute solution is a solution that contains very little solute.
d) A concentrated solution is a solution that contains a lot of solute.
e) A saturated solution is a solution that contains the maximum amount solute and cannot be dissolved any more at the given temperature.
 |
| The differences between a solution and a suspension |
g) A suspension is a cloudy mixture containing insoluble sediments (tiny particles of solid matter floating in it which will eventually settle to the bottom).
h)The solubility of a substances is
i) the maximum mass of the substances(solute) that can dissolve in 100 cm³ of the solvent at a specific temperature.
ii) varies with temperature
 |
| characteristics of dilute solution, concentrated solution and saturated solution |
j)Examples of organic solvents that can dissolve the substances
1.Turpentine / Petrol /Kerosene dilutes paint
2.Alcohol dissolves chlorophyll
3.Acetone dissolves Nail varnish
4.Benzene dissolves Rubber
5.Alcohol dissolves Iodine
6.Chloroform dissolves Plastic
7.Toluene removes Resins
k)Properties of acidic substances
a) Tastes sour
b) pH value less than 7
c) releases nitrogen when reacted with metal
d) Changes the blue litmus paper to red.
e)React with acid to form salt and water (neutralisation)
l)Properties of alkaline substances
a) Tastes bitter
b) Feels soapy when touched
c) Changes the red litmus paper to blue.
d) pH value is higher than 7
e) React with acid to form salt and water (neutralisation)
m)Acids only show their acidic properties in the presence of water. Alkali only show their alkaline properties in the presence of water.
A) Uses of acids:
i) In the chemical industry to produce explosives,dyes,synthetic fibres and fertilisers.
ii) To preserve food
iii) To remove dust
B) Uses of alkali:
i) For making many household products such as detergent,toothpaste and soap.
ii) To neutralise acidic soil.
pH scale1)Lime water - 2 pH value (acidic)
2)Vinegar - 3 pH value (acidic)
3)Fresh milk - 6 pH value (acidic)
4)Distilled water -7 pH value (neutral)
5)Blood - 7.5 pH value (alkaline)
6)Toothpaste -9 pH value (alkaline)
7)Lime water -12 pH value (alkaline)
Neutralisation
1.Neutralisation is a process in which an acid reacts with an alkali to form a salt.
Acid + alkali --------(process:Neutralisation)--> salt + water
2. The products of neutralisation are salt and water.
3.Reaction of various kinds of acids and alkalis will produce different types of salts Examples:
Hydrochloric acid + sodium hydroxide -----> sodium chloride + water
Nitric acid + calcium hydroxide -----> calcium nitrate + water
4.The technique used in neutralisation is called titration .
5.An indicator is used to show the acidity of a solution. Example: sodium hydroxide solution + universal indicator
Application of neutralisation in daily life
1.Wasp stings are alkaline. They can be treated with vinegar ( a weak acid)
2.Bee stings are acidic. They can be treated with bicarbonate powder ( a weak alkali)
3.Toothpastes are alkaline. They neutralise the acid around the teeth. This acid is produced by the bacteria which act on the food in the mouth.
4.Too much acid in the stomach causes indigestion. The excess acid in the stomach is neutralised by medicines such as milk of magnesia ( an antacid) which contains alkalis.
5.Some plants do not grow well in soil that is too acidic. Farmers add slaked lime ( calcium hydroxide which is an alkali) to reduce the acidity of the soil.
6.Shampoos are usually slightly alkaline. They neutralise the acidic oil which the skin secretes to keep the hair healthy and strong. Hair conditioner which is slightly acidic neutralises the residue of shampoo on the hair, making the hair look smooth and shiny
The salt that is produced when neutralisation occurs depends on the type of acid and alkali used.
a) Tastes bitter
b) Feels soapy when touched
c) Changes the red litmus paper to blue.
d) pH value is higher than 7
e) React with acid to form salt and water (neutralisation)
m)Acids only show their acidic properties in the presence of water. Alkali only show their alkaline properties in the presence of water.
A) Uses of acids:
i) In the chemical industry to produce explosives,dyes,synthetic fibres and fertilisers.
ii) To preserve food
iii) To remove dust
B) Uses of alkali:
i) For making many household products such as detergent,toothpaste and soap.
ii) To neutralise acidic soil.
pH scale1)Lime water - 2 pH value (acidic)
2)Vinegar - 3 pH value (acidic)
3)Fresh milk - 6 pH value (acidic)
4)Distilled water -7 pH value (neutral)
5)Blood - 7.5 pH value (alkaline)
6)Toothpaste -9 pH value (alkaline)
7)Lime water -12 pH value (alkaline)
Neutralisation
1.Neutralisation is a process in which an acid reacts with an alkali to form a salt.
Acid + alkali --------(process:Neutralisation)--> salt + water
2. The products of neutralisation are salt and water.
3.Reaction of various kinds of acids and alkalis will produce different types of salts Examples:
Hydrochloric acid + sodium hydroxide -----> sodium chloride + water
Nitric acid + calcium hydroxide -----> calcium nitrate + water
4.The technique used in neutralisation is called titration .
5.An indicator is used to show the acidity of a solution. Example: sodium hydroxide solution + universal indicator
Application of neutralisation in daily life
1.Wasp stings are alkaline. They can be treated with vinegar ( a weak acid)
2.Bee stings are acidic. They can be treated with bicarbonate powder ( a weak alkali)
3.Toothpastes are alkaline. They neutralise the acid around the teeth. This acid is produced by the bacteria which act on the food in the mouth.
4.Too much acid in the stomach causes indigestion. The excess acid in the stomach is neutralised by medicines such as milk of magnesia ( an antacid) which contains alkalis.
5.Some plants do not grow well in soil that is too acidic. Farmers add slaked lime ( calcium hydroxide which is an alkali) to reduce the acidity of the soil.
6.Shampoos are usually slightly alkaline. They neutralise the acidic oil which the skin secretes to keep the hair healthy and strong. Hair conditioner which is slightly acidic neutralises the residue of shampoo on the hair, making the hair look smooth and shiny
The salt that is produced when neutralisation occurs depends on the type of acid and alkali used.
- Hydrochloric acid + calcium hydroxide → calcium hydroxide + water
- Nitric acid + magnesium hydroxide → magnesium nitrate + water
- Sulphuric acid + sodium hydroxide → sodium sulphate + water
Natural sources of water
1.water from natural sources contains impurities are dissolved gases, microorganisms, decaying and dissolved substances, suspended particles and wastes.
2. Some microorganisms in water can cause disease such as cholera, dysentery and typhoid .
3.Some dissolved substances in the water are poisonous and bad for our health.
4.Therefore, water must be treated before it can be used for drinking. Water can be treated in the following ways.
- Filtration
- Boiling
- Chlorination
- Distillation
A) Rainwater is a natural water that is clean compared to other sources and contains dissolved gases and a little dust.
B) Groundwater - Originates from rainwater that has seeped into the ground
- Contains dissolved substances , minerals and microorganisms
C) Riverwater - Contains dissolved and decaying substances, mud and microorganisms
D) Pond water - Contains dissolved and decaying substances, mud and microoragnisms
- Pond water is stagnant. It is dirtier than river water
E)Sea water - The dirtiest of all natural sources of water
- Contains dissolved substances especially common salt
- It is too salty for human consumption
Method of water purification
Filtration
1. Filtration removes the suspended solid particles such as clay and sand in the water.
2. The filtration process can be carried out by using sand particles as the filter .
a)This system uses layers of fine sand, coarse sand, small stones and pebbles.
b) The liquid that goes through the filter is called the filtrate and the solid material left behind in the filter is called the residue.
3.Thsi method of purification does not remove microoragnisms and dissolved substances.
4.Therefore, filtered water is unsafe for drinking.
Boiling
1.Water from natural sources may contain microorganisms. These microorganisms can cause disease
such as cholera, diarrhoea and typhoid
2. Boiling can kill most of the microorganisms in the water.
3. This method can only supply a small amount of water safe for drinking at home.
4. However, boiling does not remove suspended particles and dissolved substances in the water.
Chlorination
1. Adding chlorine to water also kills microorganisms in it.
2. This method is used to treat large quantities of water.
3. The chlorination process is usually used in water purification plants and swimming pools.
4. However, too much chlorine in water gives the water an unpleasant smell and is bad for health.
Distillation
1. Distillation of water products pure water . This water is free from microorganisms , dissolved substances and suspended particles.
2. Pure water that is produced through distillation is called distilled water.
Methods of conserving water
1.Water is a precious commodity. As consumers, we should be more responsible when using water. In this way, we will be able to overcome wastage and water shortage.
2. We can save water by
a) using a tumbler and not leave a tap running when brushing and rinsing our teeth.
b)turning off the shower when soaping the body
c)using bucket of water instead of a hose to wash cars and floors.
d)replacing old flushing cisterns with new dual-flush water cisterns that use less water.
e)installing water-saving device such as self-closing delayed action water taps.
f)saving the water used for washing vegetables and fruits to water potted plants.
g)saving bathing water used for washing vegetables and fruits to water potted plants.
h)collecting rainwater to wash floors, cars and tools.
i)channeling rainwater to huge underground reservoirs.
j)treating waste water from sinks and baths to flush toilets.
k)reporting water leakages to the authorities immediately.
l)recycling water; this is especially useful for factories that use a lot of water.
The water treatment process
1. Screening removes solid particles from water.
2.Coagulation removes dirt and other particles suspended in water. Alum and slaked lime are added to water. Alum and slaked are added to water. Alum makes the particles form larger solid lumps which sink to the bottom during sedimentation. Lime reduces the acidity of water.
3.Sedimentation - the heavy particles settle to the bottom of the tanks and the clear water moves to the filter tank.
4.Filtration - The water passes through sand filter that removes smaller particles.
5. Chlorination and fluoridation - A small amount of chlorine is added to kill bacteria and microorganisms in the water. Some fluoride salt is added to prevent tooth decay.
6. Storage - Water is stored in a closed tank or reservoir for a day or two to kill all the bacteria in the water.
7. Service reservoir- Water flows through pipes to homes and factories.
a)Water Pollution -water pollutants come from industrial waste, domestic waste, chemicals, agricultural activities,mining activities, siltation, and oil spillage from tankers.
b) Industrial waste - Factory waste includes inorganic solids and toxic chemicals. Examples of such chemicals are alkalis, acids, mercury, lead, cyanide and radioactive substances.
- Factory waste is discharged into rivers and seas, polluting the water and poisoning aquatic life.
c) Domestic waste - Domestic waste which is thrown into drains results in water pollution.
- Pollutants from homes include garbage, untreated sewage and detergents.
- Non-biodegradable detergents, plastic bags and styrofoam articles which cannot be broken down into harmless substances can pollute water for many years. They are harmful to plants and small animals.
- Sewage is waste matter that is dissolved or suspended in water. It has a high content of human faeces and urine.
- Domestic rubbish includes leftover food and wastes such as paper, plastic , glass and metal.
d)Agricultural waste - In agricultural, the use of chemical fertilisers, pesticides, insecticides, herbicides and fungicides can pollute water.
-These substances leach into the ground and enter the water source in the soil which later flows into rivers, ponds and lakes.
e) Siltation - When forests are cut down and construction activities are carried out, the mud and silt flow into rivers and lakes.
f) Oil spills - Oil spills occur when oil tankers are involved in accidents with other ships at sea.
- The seas are also polluted with oil that comes from the illegal cleaning of oil tankers while at sea.
- The layer of oil that forms on the surface of the sea does not dissolve in water. The oil spreads quickly and soon forms a large area on the surface of the sea . This layer of oil kills animals in the sea and ruins beaches when it turns the shores black and sticky.
Effect of water pollution on living things
1.By-products, toxic substances and radioactive substances from factories:
a) Radioactive waste substances can cause cancer
b) Mercury, lead and heavy metals from the water will accumulate in the tissues and organs of animals through the food chain.
c) These harmful metals may end up being consumed by humans when they eat these animals.
2. Domestic waste
a) People who drink water that has been polluted by domestic waste can be infected with diseases such as cholera, dysentery and typhoid.
b) This polluted water can also cause skin diseases if it is used for washing clothes and bathing.
c) As bacteria and algae grow in polluted water, they use up oxygen. The decaying organic substances also reduces the dissolved oxygen supply in the water. As a dissolved oxygen supply in the water. As a result, many aquatic living things will die. The decaying matter will emit a bad smell.
3. Chemical substances from the agricultural sector:
a) Fertilisers that flow into rivers will cause algae to grow fast. Their growth prevents sunlight from reaching the plants in the water.
b) The aquatic plants die. The river ecosystem will be affected. Many aquatic animals will also die as a result of a lack of oxygen in the water.
c) Most pesticides, insecticides. herbicides and fungicides are not easily broken down. These toxic substances leach into the soil. From the soil they are transferred through the food chain to animals and humans.
4. Siltation
a) Mud pollutes rivers and lakes.
b) Mud prevents sun;light from entering the water. As a result, plants cannot carry out photosynthesis and die.
5.Oil spills
a) The layer of oil that forms on the surface of the sea prevents sunlight and air from entering the water.The plants and animals in the water will die.
b) Seabirds, fish and other aquatic organisms are killed because the oil is toxic.
c) Polluted beaches endanger the organisms which live along the beach areas.
d) Fisherman depend on the sea for their livelihood. So they suffer economic hardship.
Controlling water pollution
1. Water pollution is a serious and complex problem in Malaysia.
2. Several approaches can be used to control water pollution:
a) Holding campaign to prevent water pollution. These campaign educate the public on the dangers of water pollution and suggest ways to prevent water pollution.
b) Implementing laws under the Environmental Quality Act ( Scheduled Wastes) 1989 on the disposal of chemical wastes, rubbish, carcasses and faeces into rivers and seas.
c) Rubbish should be placed in the designated dumps. They should not be thrown directly into drains , rivers or seas.
d) The use of fertilisers, fungicides and pesticides must be controlled to reduce water pollution . Safer alternative methods such as biological control can be used in the agricultural sector .
e) Recycling paper, plastic , glass and metals prevents these materials from ending up in drains and rivers.
f) Waste products from factories have to be treated. This is to make sure that they are not harmful before they are disposed of into the public sewage system.
g) The authorities should implement a system of detecting oil spills in the Straits o f Malacca and the South China Sea. This system will ensure that oil spills are detected immediately . Quick action can be taken to prevent the situation from worsening . Offenders can be prosecuted under the law.
h) The main steps to water pollution control are prevention, monitoring and enforcement.
Conservation and preservation of water quality
1.Industries have policies and the technology to achieve their business objectives. At the same time, these policies should also preserve the quality of water.
2.A factory that has caused water pollution must be responsible for its actions. It must pay compensation for the damages brought about its activities.
3. Projects such as building hotels and rest houses along beach areas to attract tourists may cause pollution of the seas and beaches. Therefore, a carefully planned construction strategy should be followed.
4.Cleaning agents that are used in homes are mostly petrochemicals are available. The public should be encouraged to use these new cleaning agents.
5.In the agricultural sector, steps should be taken to reduce the use of pesticides , fungicides and fertilisers. These chemicals pollute the water.
6.To control pests, biological control methods can be used . For examples, owls can be used to control rats which eat the oil palm fruit.
7.In the education sector, environmental education should be incorporated into the school curriculum. This will make students aware of the water pollution problem . Students will know the effects and consequences of water pollution. They will learn about ways to control this problem.
8.Educational programmes for the community should be carried out. This increases the public awareness of conserving water, reducing dangerous wastes and recycling to preserve water quality.
9.As part of the efforts to preserve water quality, recycling should be carried out. Wastes which can be recycled include old newspapers, glass, aluminium tins, old tyres and plastic.
10.We should make an effort to conserve and preserve water quality.The first step must come from from us.We are the ones who determine the water quality in our country.
3.Some dissolved substances in the water are poisonous and bad for our health.
4.Therefore, water must be treated before it can be used for drinking. Water can be treated in the following ways.
- Filtration
- Boiling
- Chlorination
- Distillation
A) Rainwater is a natural water that is clean compared to other sources and contains dissolved gases and a little dust.
B) Groundwater - Originates from rainwater that has seeped into the ground
- Contains dissolved substances , minerals and microorganisms
C) Riverwater - Contains dissolved and decaying substances, mud and microorganisms
D) Pond water - Contains dissolved and decaying substances, mud and microoragnisms
- Pond water is stagnant. It is dirtier than river water
E)Sea water - The dirtiest of all natural sources of water
- Contains dissolved substances especially common salt
- It is too salty for human consumption
Method of water purification
Filtration
1. Filtration removes the suspended solid particles such as clay and sand in the water.
2. The filtration process can be carried out by using sand particles as the filter .
a)This system uses layers of fine sand, coarse sand, small stones and pebbles.
b) The liquid that goes through the filter is called the filtrate and the solid material left behind in the filter is called the residue.
3.Thsi method of purification does not remove microoragnisms and dissolved substances.
4.Therefore, filtered water is unsafe for drinking.
Boiling
1.Water from natural sources may contain microorganisms. These microorganisms can cause disease
such as cholera, diarrhoea and typhoid
2. Boiling can kill most of the microorganisms in the water.
3. This method can only supply a small amount of water safe for drinking at home.
4. However, boiling does not remove suspended particles and dissolved substances in the water.
Chlorination
1. Adding chlorine to water also kills microorganisms in it.
2. This method is used to treat large quantities of water.
3. The chlorination process is usually used in water purification plants and swimming pools.
4. However, too much chlorine in water gives the water an unpleasant smell and is bad for health.
Distillation
1. Distillation of water products pure water . This water is free from microorganisms , dissolved substances and suspended particles.
2. Pure water that is produced through distillation is called distilled water.
Methods of conserving water
1.Water is a precious commodity. As consumers, we should be more responsible when using water. In this way, we will be able to overcome wastage and water shortage.
2. We can save water by
a) using a tumbler and not leave a tap running when brushing and rinsing our teeth.
b)turning off the shower when soaping the body
c)using bucket of water instead of a hose to wash cars and floors.
d)replacing old flushing cisterns with new dual-flush water cisterns that use less water.
e)installing water-saving device such as self-closing delayed action water taps.
f)saving the water used for washing vegetables and fruits to water potted plants.
g)saving bathing water used for washing vegetables and fruits to water potted plants.
h)collecting rainwater to wash floors, cars and tools.
i)channeling rainwater to huge underground reservoirs.
j)treating waste water from sinks and baths to flush toilets.
k)reporting water leakages to the authorities immediately.
l)recycling water; this is especially useful for factories that use a lot of water.
The water treatment process
1. Screening removes solid particles from water.
2.Coagulation removes dirt and other particles suspended in water. Alum and slaked lime are added to water. Alum and slaked are added to water. Alum makes the particles form larger solid lumps which sink to the bottom during sedimentation. Lime reduces the acidity of water.
3.Sedimentation - the heavy particles settle to the bottom of the tanks and the clear water moves to the filter tank.
4.Filtration - The water passes through sand filter that removes smaller particles.
5. Chlorination and fluoridation - A small amount of chlorine is added to kill bacteria and microorganisms in the water. Some fluoride salt is added to prevent tooth decay.
6. Storage - Water is stored in a closed tank or reservoir for a day or two to kill all the bacteria in the water.
7. Service reservoir- Water flows through pipes to homes and factories.
a)Water Pollution -water pollutants come from industrial waste, domestic waste, chemicals, agricultural activities,mining activities, siltation, and oil spillage from tankers.
b) Industrial waste - Factory waste includes inorganic solids and toxic chemicals. Examples of such chemicals are alkalis, acids, mercury, lead, cyanide and radioactive substances.
- Factory waste is discharged into rivers and seas, polluting the water and poisoning aquatic life.
c) Domestic waste - Domestic waste which is thrown into drains results in water pollution.
- Pollutants from homes include garbage, untreated sewage and detergents.
- Non-biodegradable detergents, plastic bags and styrofoam articles which cannot be broken down into harmless substances can pollute water for many years. They are harmful to plants and small animals.
- Sewage is waste matter that is dissolved or suspended in water. It has a high content of human faeces and urine.
- Domestic rubbish includes leftover food and wastes such as paper, plastic , glass and metal.
d)Agricultural waste - In agricultural, the use of chemical fertilisers, pesticides, insecticides, herbicides and fungicides can pollute water.
-These substances leach into the ground and enter the water source in the soil which later flows into rivers, ponds and lakes.
e) Siltation - When forests are cut down and construction activities are carried out, the mud and silt flow into rivers and lakes.
f) Oil spills - Oil spills occur when oil tankers are involved in accidents with other ships at sea.
- The seas are also polluted with oil that comes from the illegal cleaning of oil tankers while at sea.
- The layer of oil that forms on the surface of the sea does not dissolve in water. The oil spreads quickly and soon forms a large area on the surface of the sea . This layer of oil kills animals in the sea and ruins beaches when it turns the shores black and sticky.
Effect of water pollution on living things
1.By-products, toxic substances and radioactive substances from factories:
a) Radioactive waste substances can cause cancer
b) Mercury, lead and heavy metals from the water will accumulate in the tissues and organs of animals through the food chain.
c) These harmful metals may end up being consumed by humans when they eat these animals.
2. Domestic waste
a) People who drink water that has been polluted by domestic waste can be infected with diseases such as cholera, dysentery and typhoid.
b) This polluted water can also cause skin diseases if it is used for washing clothes and bathing.
c) As bacteria and algae grow in polluted water, they use up oxygen. The decaying organic substances also reduces the dissolved oxygen supply in the water. As a dissolved oxygen supply in the water. As a result, many aquatic living things will die. The decaying matter will emit a bad smell.
3. Chemical substances from the agricultural sector:
a) Fertilisers that flow into rivers will cause algae to grow fast. Their growth prevents sunlight from reaching the plants in the water.
b) The aquatic plants die. The river ecosystem will be affected. Many aquatic animals will also die as a result of a lack of oxygen in the water.
c) Most pesticides, insecticides. herbicides and fungicides are not easily broken down. These toxic substances leach into the soil. From the soil they are transferred through the food chain to animals and humans.
4. Siltation
a) Mud pollutes rivers and lakes.
b) Mud prevents sun;light from entering the water. As a result, plants cannot carry out photosynthesis and die.
5.Oil spills
a) The layer of oil that forms on the surface of the sea prevents sunlight and air from entering the water.The plants and animals in the water will die.
b) Seabirds, fish and other aquatic organisms are killed because the oil is toxic.
c) Polluted beaches endanger the organisms which live along the beach areas.
d) Fisherman depend on the sea for their livelihood. So they suffer economic hardship.
Controlling water pollution
1. Water pollution is a serious and complex problem in Malaysia.
2. Several approaches can be used to control water pollution:
a) Holding campaign to prevent water pollution. These campaign educate the public on the dangers of water pollution and suggest ways to prevent water pollution.
b) Implementing laws under the Environmental Quality Act ( Scheduled Wastes) 1989 on the disposal of chemical wastes, rubbish, carcasses and faeces into rivers and seas.
c) Rubbish should be placed in the designated dumps. They should not be thrown directly into drains , rivers or seas.
d) The use of fertilisers, fungicides and pesticides must be controlled to reduce water pollution . Safer alternative methods such as biological control can be used in the agricultural sector .
e) Recycling paper, plastic , glass and metals prevents these materials from ending up in drains and rivers.
f) Waste products from factories have to be treated. This is to make sure that they are not harmful before they are disposed of into the public sewage system.
g) The authorities should implement a system of detecting oil spills in the Straits o f Malacca and the South China Sea. This system will ensure that oil spills are detected immediately . Quick action can be taken to prevent the situation from worsening . Offenders can be prosecuted under the law.
h) The main steps to water pollution control are prevention, monitoring and enforcement.
Conservation and preservation of water quality
1.Industries have policies and the technology to achieve their business objectives. At the same time, these policies should also preserve the quality of water.
2.A factory that has caused water pollution must be responsible for its actions. It must pay compensation for the damages brought about its activities.
3. Projects such as building hotels and rest houses along beach areas to attract tourists may cause pollution of the seas and beaches. Therefore, a carefully planned construction strategy should be followed.
4.Cleaning agents that are used in homes are mostly petrochemicals are available. The public should be encouraged to use these new cleaning agents.
5.In the agricultural sector, steps should be taken to reduce the use of pesticides , fungicides and fertilisers. These chemicals pollute the water.
6.To control pests, biological control methods can be used . For examples, owls can be used to control rats which eat the oil palm fruit.
7.In the education sector, environmental education should be incorporated into the school curriculum. This will make students aware of the water pollution problem . Students will know the effects and consequences of water pollution. They will learn about ways to control this problem.
8.Educational programmes for the community should be carried out. This increases the public awareness of conserving water, reducing dangerous wastes and recycling to preserve water quality.
9.As part of the efforts to preserve water quality, recycling should be carried out. Wastes which can be recycled include old newspapers, glass, aluminium tins, old tyres and plastic.
10.We should make an effort to conserve and preserve water quality.The first step must come from from us.We are the ones who determine the water quality in our country.
not enough notes
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Deletemore than enough.thanks sir,be grateful that someone is giving you knowledge.so zip it
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