Chapter5waterandsolution 121120021919-phpapp01
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Water is the most abundant substance on Earth and exists in three states: solid, liquid, and gas. It has unique physical characteristics like being colorless, odorless, and tasteless as a liquid. Its freezing point is 0°C and boiling point is 100°C. Water is made of hydrogen and oxygen atoms and is represented by the formula H2O. Natural sources of water include oceans, lakes, rivers, and groundwater but require purification for human use and consumption. Common purification methods include filtration, boiling, and chlorination which remove various impurities while distillation produces the purest form of water.
Chapter5waterandsolution 121120021919-phpapp01
- 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. A. Physical Characteristics of Water 1. Water can exist in three states: a. Solid b. Liquid c. Gas 5.1 Physical Characteristics of Water
- 4. 2. At room temperature, pure water is a a. colourless, b. odourless and c. tasteless. 5.1 Physical Characteristics of Water
- 5. liquid solid Freezing point of water is the temperature at which water freezes into ice. 5.1 Physical Characteristics of Water Freezing Point of Water 1.Water changes from liquid to solid at its freezing point.
- 6. 2. The freezing point of pure water is 0 oC. 3. The temperature remains constant at 0 oC until water freezes completely. 5.1 Physical Characteristics of Water
- 7. 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! 5.1 Physical Characteristics of Water
- 8. liquid gases Boiling point of water is the temperature at which water boils and becomes steam. 5.1 Physical Characteristics of Water Boiling Point of Water 1. Water boils at its boiling point.
- 9. 2. The boiling point of pure water is 100 oC. 3. The temperature remains constant at 100 oC until water boils completely. 5.1 Physical Characteristics of Water
- 10. 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! 5.1 Physical Characteristics of Water
- 11. 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. 5.1 Physical Characteristics of Water
- 12. 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. 5.1 Physical Characteristics of Water
- 13. Physical characteristic Example Taste Purewateristastelessbutseawaterissalty. Odour Purewaterisodourless.Waterwithdecayedmatterhasanunpleasant smell. Colour Purewateriscolourlessbutmuddywaterisbrownishincolour. Density Purewaterislessdensethanseawater. Electricalconductivity Purewaterwithafewdropsofsulphuricacidcanconductelectricity. Freezingpoint o Purewaterfreezesat0Cbutseawaterfreezesatalower temperature. Boilingpoint o Purewaterboilsat100Cbutseawaterboilsatahighertemperature. 2. Here are some examples: 5.1 Physical Characteristics of Water
- 14. Hydrogen Oxygen 5.2 Composition of Water Composition of Water 1. Water is a compound. It is made of two different elements. Water
- 15. 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 5.2 Composition of Water
- 16. Hydrogen is released at the cathode Oxygen is released at the anode 5.2 Composition of Water 3. The volume of hydrogen released is always twice the volume of oxygen released.
- 17. Hydrogen atoms Each water molecule consists of one atom of oxygen and two atoms of hydrogen. 5.2 Composition of Water Water is made up of one part of oxygen and two parts of hydrogen. Oxygen atom 4.
- 18. 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 5.2 Composition of Water
- 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. Solution and Solubility 5.4 Solution and Solubility
- 21. 1. What is a solution? • A solute is the substance that dissolves. • A solvent is the substance that the solute dissolves in. 5.4 Solution and Solubility
- 22. Dilute solution Contains a little dissolved solute Can dissolve a lot more solute Concentrated solution Contains a lot of dissolved solute Can dissolve a little bit more solute Saturated solution Contains the maximum amount of dissolved solute Cannot dissolve any more solute All these solutions have a clear appearance 5.4 Solution and Solubility 2. Depending on the amount of solutes in solutions, there are three types of solutions. Solution
- 23. 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 5.4 Solution and Solubility
- 24. 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. 5.4 Solution and Solubility
- 25. 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 5.4 Solution and Solubility
- 26. 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. 5.4 Solution and Solubility
- 27. 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. 5.4 Solution and Solubility
- 28. 1. What are the factors affecting the rate of dissolving a solute? a. Temperature b. Rate of stirring c. Size of solute particles 5.4 Solution and Solubility
- 29. 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. 5.4 Solution and Solubility
- 30. 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. 5.4 Solution and Solubility
- 31. 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. 5.4 Solution and Solubility
- 32. 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. 5.4 Solution and Solubility
- 33. 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. 5.4 Solution and Solubility
- 34. • Alcohol • Turpentine • Acetone 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:
- 35. 1. We use many organic solvents in various products. To produce lacquers and varnishes Alcohol Turpentine Acetone To produce various types of ink To prepare iodine solution (as an antiseptic) To produce perfume To produce paints To remove paint stains To produce nail polish To remove nail polish 5.4 Solution and Solubility
- 36. 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). 5.4 Solution and Solubility
- 37. 1. 2. An acid is a substance that has a hydrogen atom, which can be replaced by a metal or ammonium. Acid can be divided into two groups and differences are shown below
- 38. ACID Organic acid Example Acetic acid Formic acid Lactic acid Malic acid Citric acid Tannic acid Tartaric acid Inorganic acid Example Sulphuric acid Nitric acid Hydrochloric acid Carbonic 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. g. React with alkalis to form salt and water acid + metal salt + hydrogen acid + alkali salt + water
- 41. 1. 2. An alkalis is hydroxide or metal oxide that dissolves in water. Example: potassium hydroxide, sodium hydroxide, calcium hydroxide, ammonium hydroxide solutions.
- 42. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 neutral Acidity increases Alkalinity increases
- 43. acid + alkali salt water+ Note: Neutralisation Neutralization is a process where Where acid reacts with alkali, salt and water are formed. Different kinds of acids and alkalis will form different types of salt. 5.5 Acid and Alkali
- 44. Natural Sources of Water Natural Sources of Water From Ocean • Salty • Not suitable for human consumption From lakes, streams, rivers, ground water (well) and rain • Fresh Water • But not pure, need to be purified 5.6 Water Purification
- 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. Usage of Water Usage of Water Domestic Use of Water • Drinking • Washing • Watering Plants Agricultural Use of Water • Irrigation • Aquaculture • • • Direct Use of Rivers and Streams Generate Hydroelectric Power Recreation Transportation Industrial Use of Water • Cooling • Washing • Disposal of Waste 5.7 Water Supply System
- 50. Chlorine solution METHOD OF PURIFICATION Chlorination
- 51. Filtration Muddy water Fine sand Coarse sand Pebbles Gravel filtrate
- 52. filtrate Boiling
- 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 Onlyremoves impuritiesthatare coarsesuchas suspendedsubstances. Sandfiltersare commonlyused Waterisclear andfree suspended particlesonly Waterstillhas microorganisms anddissolved substances (suchas mineralsalts)
- 56. b. Distillation Prepares pure or distilled water Water is free from all suspended substances, microorganisms and dissolved substances. Water does not make good drinking because it does not contain dissolved mineral with our body need.
- 57. c. Boiling and chlorination Only kills microorganisms in water Water is free from dangerous microorganisms Water still has dissolved substances and 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.