Modern Concept Science and Technology 10 New

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 397 d. Which gas is obtained by reacting slaked lime and ammonium chloride? e. What is a promoter? Give an example of it. f. Name two chemicals that are required to prepare ammonia in the laboratory. Mention their ratio by mass. g. Which gas is obtained by reacting limestone and dilute hydrochloric acid? h. Which gas is produced by the chemical reaction of dilute hydrochloric acid and egg shells? i. Name the gas produced when a mixture of ammonium chloride and calcium hydroxide is heated. j. Write the use of the lime tower. Which chemical compound is kept in it? k. Name two chemicals which are required to prepare carbon dioxide in the laboratory. l. Name two greenhouse gases. m. What is an artificial house made of glass to trap heat called? n. Give any two examples of industrial gases. o. Which gas is used as a coolant in a refrigerator? p. What are the conditions required for Haber’s process? STEP2 4. Give reasons. a. Carbon dioxide is not collected over water. b. A moist red litmus paper is used for testing ammonia. c. Ammonia cannot be collected in an erect gas jar. d. Concentrated sulphuric is not used to remove moisture from ammonia. e. Carbon dioxide is important for green plants. f. Carbon dioxide can be tested with the help of moist blue litmus paper. g. Carbon dioxide is used as a fire extinguisher. h. It is dangerous to clean a well remaining closed for a long time. i. Lime water turns milky when carbon dioxide is passed through it. j. Greenhouse gases are very important for farmers. k. Natural greenhouse effect of the earth makes earth suitable for living things to survive. l. Fossil fuel should be replaced by electricity to save the environment. m. Over-greenhouse effect is harmful to human health. n. It's always warm inside the artificial greenhouse than in the surrounding. o. Artificial greenhouse has a slanted roof.

398 Some gaSeS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur p. Acid rain is a disaster. q. Cities are more affected by acid rain. r. Its warmer when sky is covered with a stratus cloud than a clear sky. 5. Differentiate between the following. a. Ammonia and carbon dioxide b. Artificial greenhouse and natural greenhouse 6. Answer the following questions in short. a. Where is carbon dioxide found in nature? What is its source? b. What happens when burning magnesium is inserted in the jar containing carbon dioxide? Write the chemical equation. c. Write any two physical and chemical properties of carbon dioxide. d. Write any two physical and chemical properties of ammonia. e. Write any three uses of carbon dioxide. f. Write any three precautions that should be adopted during the laboratory preparation of ammonia. g. Write any three uses of ammonia. h. What will happen to life if the earth stops working as a natural greenhouse? i. What are the effects of the greenhouse effect? Enlist them. j. Write down the importance of the artificial greenhouse. k. What happens when a burning match stick is dropped in carbon dioxide gas? l. Why is carbon dioxide not used to fill balloons? m. What happens if a mixture of sodium hydroxide and ammonium sulphate is warmed? n. When a rod dipped in hydrochloric acid is put in ammonia gas, a white smoke is formed. Write the name of the compound that makes the smoke. o. What can we do to reduce acid rain and its impacts? 7. Answer the following questions on the basis of the given figure. i. Name the gas which is being produced in the diagram. ii. Why is the gas jar kept erect? iii. How can we test this gas? iv. Which litmus paper is used to test this gas? v. How is this gas collected? dil.HCl Gas

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 399 STEP3 8. Answer the following questions. a. How is carbon dioxide prepared in the laboratory? Write with the balanced chemical equation. b. Draw a neat and labelled diagram showing laboratory preparation of carbon dioxide. c. What are three precautions that should be adopted during the preparation of carbon dioxide in the laboratory? d. Write any three methods for testing carbon dioxide. e. How is ammonia prepared in the laboratory? Write with the balanced chemical equation. f. Draw a neat and labelled diagram showing the laboratory preparation of ammonia. g. Mention any three methods for testing ammonia in the laboratory. h. How is urea prepared from ammonia? Describe in brief. i. How is ammonia prepared on an industrial scale? Describe. j. Write down the importance of the greenhouse effect. k. Describe the formation of acid rain. Mention its harmful effects. 9. Answer the following questions on the basis of the given figure. a. Laboratory preparation of ammonia is given in the figure. What is the method to test whether the gas jar is full or not? Why cannot this gas be collected in the gas jar by downward displacement of water? Mixture of Ca(OH)2 and NH4 Cl Ammonia gas Lime tower CaO Burner Stand Stand

400 Some gaSeS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur b. The given figure shows the laboratory preparation of ammonia gas. Answer the following questions after observing the given figure. i. Write the balanced chemical reaction of laboratory preparation of ammonia by this method. ii. Why is the mouth of a hard glass test tube inclined downward? iii. Which litmus paper (red or blue) help to confirm that the gas jar is filled with ammonia? c. Answer the following questions based on the given diagram. i. Which gas is being collected in the gas jar? ii. What happens when some lime water is put in the gas jar? iii. Write down the balanced chemical equation of the chemical reaction in the formation of the given gas. d. Observe the given instrument and answer the following questions. i. What is the name of the given instrument? ii. What is the name of chemical A and Chemical B? Write down the balanced chemical equation between them. iii. What is the purpose of this instrument? iv. Why is A kept in a glass container? dil.HCl Woulfe’s bottle Pieces of CaCO3 Delivery tube

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 401 Key terms and terminologies of the unit 1. Metals : Metals are elements (except hydrogen) which form electropositive ions by losing electrons. 2. Minerals : Minerals are those naturally occurring chemical substances which contain metals more or less in amount. 3. Ores : Those minerals from which metals can be extracted conveniently and profitably are called ores. 4. Metallurgy : Metallurgy is the process by which we can get pure metals from their ores. 5. Ores of Iron : Haematite, Magnetite, Siderite , Limonite and Iron pyrite 6. Ores of Aluminium : Bauxite, Cryolite and Feldspar 7. Ores of Copper : Copper pyrite or chalcopyrite , Cuprite, Chalcocite or Copper glance, Malachite and Azurite. 8. Ores of Silver : Argentite or silver glance, Horn silver, Silver copper glance and Ruby silver or pyrolite 9. Ores of Gold : Gold is present in alluvial sand or alluvial soil or quartz veins and calaverite (AuTe2 ). Introduction Metals are elements (except hydrogen) which form electro-positive ions by losing electrons. Metals are good conductors of heat and electricity. They are malleable and ductile. Therefore, metals are widely used in our daily life. Among the many metals, iron, aluminium, copper, silver and gold are commonly used in our day-to-day life. Iron and steel are used Sequence of Curriculum Issued by CDC  Metals: concept of minerals and ores  Names of chief ores of iron, copper, silver and aluminium  Metallurgy: mining, grinding, concentration, smelting, roasting and electro refining (without chemical equations) UNIT Metals 17 Estimated teaching period Theory Practical 4 1 Georgius Agricola is called the father of metallurgy or mineralogy because of his research and development of complex processes of mining metal ores, metal extraction and metallurgy of that time. He was born in the Roman empireon 13th June 1494 and died on 21st November 1555. He was a German Humanist scholar, mineralogist and metallurgist. He published over 40 complete scholarly works during his professional life on a wide range of subjects and disciplines, such as pedagogy, medicine, metrology, pharmacy, philosophy, etc. Georgius Agricola About the Scientist

402 metalS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur in construction works, industries, for making vehicles, cooking utensils, weapons, etc. Aluminium is extensively used for making household utensils, coins, bodies and parts of aeroplanes, ships, etc. Copper is widely used for making electric wires, household utensils, coins, etc. Similarly, silver and gold are also used for making ornaments, medals, coins, idols, etc. In this unit, we will study the occurrence, ores, extraction, properties and uses of some common metals, viz. iron, aluminium, copper, silver and gold. Minerals Minerals are those naturally occurring chemical substances which contain metals more or less in amount. For example, limestone, slate, kaolin, haematite, etc. All minerals are not suitable for extracting metals because some of them contain very little metal but some contain more amounts of metals. That is why certain minerals are suitable for extraction of metals. Such minerals are called ores. Ores Those minerals from which metals can be extracted conveniently and profitably are called ores. An ore contains a good percentage of metal and there are few impurities in it. For example, magnetite, cuprite, bauxite, etc. Differences between Minerals and Ores. SN. Minerals SN. Ores 1. They contain metals in some amount. 1. They contain metals in more amount. 2. From all minerals, we cannot extract metals. 2. From all ores, we can extract metals. 3. All minerals are not ores. 3. All ores are minerals. Metallurgy Metallurgy is the process by which we can get pure metals from their ores. Metallurgy involves several steps. The main steps are given below: i. Crushing of ore This step is used to convert big pieces of ores into smaller ones. ii. Powdering of ore In this step, pieces of ores are converted into powder form. iii. Concentration of ore In this step, unwanted earthy substances like soil, sand, limestone, etc. are removed. There are various methods of concentration of ores. Among them, magnetic method is used to separate magnetic and non-magnetic substances, froth floatation method is used to separate hydrophilic and hydrophobic substances, gravity separation is used to separate heavy and light substances, etc. MEMORY TIPS All minerals are not ores but all ores are minerals. MEMORY TIPS Mining is a process in which ores of various metals are taken out from the earth crust.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 403 a. Gravity separation / hydraulic separation This process is employed if the impurities are lighter (less dense) than ores. The lighter particles of impurities are washed away with the help of water current. Fig: gravity separation b. Forth floatation This process is employed if the impurities are hydrophilic or hydrophobic. It is applicable mostly for sulphide ores. Here, the powder is mixed with water along with pine oil. The mixture is agitated by passing current of air. As a result, ores come to the surface and impurities remain at the bottom. c. Magnetic separation This process is applicable only if the impurities or the ores are magnetic in nature. For this separation, powder ore is dropped on the moving belt of the magnetic roller. Finally, two heaps are formed, one for the magnetic substance and another for the non-magnetic substance. d. Chemical separation (leaching) This process is applied when ores and impurities have different chemical properties. Usually powdered ores are dissolved in strong alkali solution where metal gets dissolved in solution and can be extracted later. Fig: froth floatation Fig: Chemical separation (leaching)

404 metalS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur iv. Oxidation of Metal a. Calcination By this process, carbonate and hydroxide ores are strongly heated in limited air below the melting point of a metal to get metallic oxides. b. Roasting By this process, sulphide ores are strongly heated in the presence of excess air below the melting point of metal to get metallic oxides. v. Reduction of metal oxides In this process, free metal is obtained from the corresponding metal oxides. To convert metal oxides into free metals, different types of reducing agents like coke, hydrogen, carbon monoxide, etc. are used. If reduction process is carried out in the presence of coke, it is called smelting. Smelting In this process, we get free metals from their oxides. vi. Refining of metal Here, we obtain pure metal by using different types of refining methods like oxidation, distillation, evaporation, electrorefining, etc. a. Distillation: In this method, metal is purified by boiling the mixture. If one of the substances among metal and impurities escapes out through vapour, this method is applied. b. Electro-refining: It is most popular method of metal refining. In this method, impure metal is connected to the anode, pure metal is connected to the cathode and we keep electrolyte of the anodic salt solution in the voltameter. For example, for copper refining, pure copper is taken at cathode, impure copper is taken at anode and we use copper sulphate salt solution as an electrolyte. ACTIVITY 1 Take an impure copper plate and connect it to the positive terminal (anode) of dry cell. Take a small piece of pure copper and connect it to the negative terminal (cathode) of dry cell. Dissolve copper sulphate in the water contained in the voltameter. Supply the electric current for some duration and observe the changes in the electrodes. Iron, aluminium, copper, silver and gold are some important metals used in our daily life. The occurrence, extraction, properties and uses of these metals are described below: Fig: Copper refining

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 405 Iron Symbol Fe Atomic number 26 Atomic weight 56 Valency 2 or 3 Electronic configuration 1s2 , 2s2 2p6 , 3s2 3p6 , 4s2 ,3d6 Position in periodic table Period = 4, Group = 8, Block = d – Block Occurrence Iron is one of the reactive metals. So, it does not occur in a free state in nature. It forms different types of compounds, like oxides, sulphides, chlorides, hydroxides, carbonates, etc. A little amount of iron is present in the haemoglobin of our blood. Ores of Iron 1. Haematite Fe2O3 (chief ore) 2. Magnetite Fe3O4 3. Siderite FeCO3 4. Limonite 2Fe₂O3 . 3H₂O 5. Iron pyrite FeS2 Among the different ores of iron, haematite contains about 72.5% of iron. It is an easily available ore. So, iron is generally extracted from this ore. Physical Properties of Iron i. Iron is a shiny and gray white, i.e., ash colored metal. ii. Its specific gravity is 7.86. iii. Its melting point is 15000 C and boiling point is 25000 C. iv. It is a good conductor of heat and electricity. v. It is malleable and ductile. vi. It becomes non-magnetic when heated above 7700 C. Uses of Iron i. Iron is used to make different types of household utensils. ii. It is used for making rods, pipes, wires, bolts, materials for building construction, bridges, parts of vehicles, railway tracks, tools, weapons, etc. iii. It is used as a catalyst in various chemical reactions. iv. It is used in the manufacture of steel. Aluminium Symbol Al Atomic number 13 Atomic weight 27 Haematite ore

406 metalS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Electronic configuration 1s2 , 2s2 2p6 , 3s2 3p1 Valency 3 Position in periodic table Period – 3, Group - 13, Block = p – Block Occurrence Aluminium is the most abundant metal on the earth's crust. It does not occur in a free state. In combined state, it is present in different types of compounds, like oxides, fluorides, sulphates, etc. Aluminium is highly malleable and ductile. Hence, it is used to make foils in packing and wires of electricity. Ores of Aluminium 1. Bauxite Al2O3.2H2O (chief ore) 2. Cryolite Na₃AlF₆ 3. Felspar K(AlSiO₃.O₈) 4. Corundum Al2 O3 Physical properties of aluminium i. Aluminium is a bluish-white metal. ii. It is highly malleable and ductile. iii. It is a good conductor of heat and electricity. iv. Its specific gravity is 2.7. v. Its melting point is 660°C and boiling point is 1800°C. vi. It is a light metal. FACTS WITH REASONS Though aluminium is a quite reactive metal, it does not react with water, why? Though aluminium is a quite reactive metal it does not react with water. This is due to the presence of an inert aluminium oxide layer on its surface which is formed when aluminium combines with the oxygen of air. This thin but strong layer prevents the reaction of aluminium with water. Aluminium is used in making bodies and parts of aeroplanes, why? Being a light and rust free metal, aluminium is used for making bodies and parts of aeroplanes. Aluminium is used for making silver paint and mirros, why? Aluminium powder is used for making silver paint because of its silvery appearance. Since aluminium is a good reflector, it is deposited on glass to make mirrors. Uses of aluminium i. Aluminium is used to make household utensils, body parts of vehicles and aeroplanes. ii. Aluminium foil is used for wrapping foods, cigarettes, pharmaceutical products, etc. iii. It is used for making coins, alloys and overhead electric cables. iv. It is used for making silver paint, mirrors, photo frames, etc. Chalcopyrite ore Bauxite ore

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 407 Copper Symbol Cu Atomic number 29 Atomic weight 63.57 Valency 1 or 2 Electronic configuration 1s2 , 2s2 2p6 , 3s2 3p6 , 3d10, 4s1 Position in periodic table Period – 4, Group - 11, Block – d – Block Occurrence Less amount of copper is found in a free state in nature. But maximum amount of it is found in a combined state in the form of sulphides, oxides and carbonates. Ores of copper 1. Copper pyrite (Chalcopyrite) CuFeS₂ 2. Cuprite Cu₂O 3. Chalcocite (copper glance) Cu₂S 4. Malachite Cu(OH)₂. CuCO₃ 5. Azurite [Cu(OH)₂. 2CuCO₃] Physical properties of copper i. It is a hard reddish brown metal. ii. It is a good conductor of heat and electricity. iii. It is malleable and ductile. iv. Its specific gravity is 8.95. v. Its melting point is 1083°C and boiling point is 2350° C. Uses of copper i. Copper is used to make household utensils, like cooking utensils, boilers, kettles, etc. ii. It is used to make electric wires and cables. iii. It is used for electroplating and electrotyping. iv. Copper salts are used as insecticides, fungicides and germicides. v. It is used for making alloys like brass, bronze, etc. vi. It is used to make coins. vii. Copper is used to make different types of alloys. Some common alloys of copper with their composition and uses are given below: Alloys Composition Uses 1. Brass Cu + Zn To make nut bolts, condenser tubes and medals 2. German Silver Cu + Zn + Ni To make utensils and bells 3. Bronze Cu + Zn + Sn To make household utensils and coins 4. Gun metal Cu + Sn + Zn + Pb To make ball bearings and parts of machines 5. Bell metal Cu + Sn To make bells and decorative items.

408 metalS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Silver Symbol Ag Atomic number 47 Atomic weight 107.88 Valency 1 Electronic configuration 1s2 , 2s2 2p6 , 3s2 3p6 , 3d10 , 4s2 , 4p6 , 4d10, 5s1 Position in periodic table Period – 5, Group - 11, Block = d – Block Occurrence Silver is a less reactive metal. It occurs in both free and combined states. In combined state, it occurs in the form of sulphide and chloride. Ores of Silver 1. Argentite (silver glance) Ag₂S 2. Horn silver AgCl 3. Silver copper glance (AgCu)₂S 4. Ruby silver (Pyrolite) 3Ag₂S.Sb₂S₃ Physical properties of silver i. It is a shiny white metal. ii. It is a good conductor of heat and electricity. iii. It is malleable and ductile. iv. Its specific gravity is 10.5. v. Its melting point is 960°C, and boiling point is 1955°C. Uses of silver i. Silver is used to make jewellery and other valuable ornaments. ii. It is used to make coins, medals, idols, statues, etc. iii. It is used for silver-plating. iv. Silver salt (like silver bromide- AgBr) is used in photography. v. Silver alloy is used for silver mirror, and for filling teeth. vi. Silver nitrate and other silver compounds are used as laboratory reagents. Gold Symbol Au Atomic number 79 Atomic weight 197.2 Valency 1 or 3 Electronic configuration 1s2 , 2s2 2p6 , 3s2 3p6 , 3d10,4s2 4p6 4d10, 4f14, 5s2 5p6 5d10, 6s1 Position in periodic table Period – 6, Group - 11, Block – d – Block Argentite ore

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 409 Occurrence Gold is a less reactive metal. So, it is found in a free state in nature. It is found in reef gold mixed with quartz or alluvial soil eroded by the river. Ores of gold Gold is present in alluvial sand or alluvial soil or quartz veins and calaverite (AuTe2 ). Extraction of gold Gold is extracted from alluvial soil or sand rich in gold. The gold containing soil is mixed with water and run on a sluice. The particles of gold get trapped in the cavities of the sluice, which are separated from the sand. Physical properties of gold i. Gold is a yellow shining metal. ii. It is a good conductor of heat and electricity. iii. It is a heavy metal with specific gravity 19.3. iv. Its melting point is 1063°C and boiling point is 2530°C. FACTS WITH REASONS Gold is found in a pure state in nature but not iron, why? Gold is a noble metal. It does not react with air, water, acids and other chemicals in normal temperature and pressure. So gold is found in a pure state. But iron combines with air, acids and other chemicals in ordinary condition to form various types of compounds. So, iron is not found in a pure state in nature. Why is gold called noble metal or neutral metal? Gold does not react with air, water, acids and other chemicals in normal temperature and pressure. So, gold is called a noble metal or neutral metal. Uses of gold i. Gold is used for making jewellery, statues and other ornaments. ii. It is used for making medals, coins, etc. iii. It is used for gold plating. iv. It is used for making a gold leaf electroscope. v. It is used for filling teeth. vi. Compounds of gold are used in the laboratory, medicines and photography. Project Work Using plastics, make an artificial greenhouse and display in the class. Calaverite ore MEMORY TIPS Gold is a less reactive metal, so it does not react with common chemical reagents like air, water, acids, etc. However, it gets dissolved in aqua regia. A mixture of 3:1 ratio of concentrated hydrochloric acid and concentrated nitric acid is known as aqua regia. It is also called kingly water because it dissolves gold to give gold chloride (AuCl3). Gold is a less reactive metal. Therefore, it is found in a free state in nature.

410 metalS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur HOT SKILL HIGHER ORDER THINKING SKILL 1. Let’s suppose you have a haematite ore, how would extract iron from it? Let’s suppose we found a haematite ore. We can extract iron from it by following metallurgical procedures. i. Mining:The haematite ore is first mined and transported to the crusher. ii. Concentration:It is crushed into powder. It is magnetic so it is concentrated by the magnet. Then it is roasted to remove water, volatile impurities and carbonates. iii. Extraction: It is mixed with limestone and coke and put in the blast furnace. A chemical reaction takes place and everything changes into ferrous oxide. Ferrous oxide burns with carbon monoxide and changes into pig iron. Iron and coke are mixed in it and subjected to a strong blast of hot air to change it into cast iron. iv. Refining: Cast iron is further heated in presence of haematite to produce wrought iron. Wrought iron is the purest form of iron. 2. The ornaments made from gold can be worn while using chemicals, pickles, washing clothes etc. Why? The ornaments made from gold can be worn while using chemicals, pickles, washing clothes etc. because gold is chemically inactive. It does not react with moisture, air, water or acids. So, we can wear it without any worries. It won’t be chemically damaged. 3. Differentiate between calculation and roasting. The differences between calcination and roasting are: SN Calcination SN Roasting 1 In calcination, the ore is heated with the least supply of air. 1 In roasting, the ore is heated with a maximum supply of air. 2 Its objective is to remove volatile impurities such as arsenic. 2 Its objective is to oxidise the impurities such as carbon and sulphur. 3 Usually, impurities are removed as carbon dioxide. 3 Usually, impurities are removed as sulphur dioxide. 4. Roasted ores are heated with hydrogen or carbon monoxide. Roasted ores are heated with hydrogen or carbon monoxide to reduce metals from their oxides. 5. Ores can be used to extract metals industrially but minerals cannot be. Ores can be used to extract metals industrially because they contain a very high concentration of metals. But minerals cannot be used to extract metals industrially because they contain low concentrations of metals. It would not be profitable to extract metals from them. 6. Gold is found in elemental form. Gold is found in elemental form because it cannot lose electrons easily. So, it cannot react with other elements to form compounds.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 411 7. An electrorefining is preferred for purifying metals. Electrorefining is preferred for purifying metals because it can extract the purest form of metals even from alloys, scraps, mixtures etc. 8. All ores are minerals but all minerals are not ores. All ores are minerals because they contain a certain percentage of metals in them. However, all minerals cannot be ore because some minerals contain less quantity of metals in them. The ore must have a higher concentration of metal in them. 9. What is the objective of calcination? Why is it important? The objective of calcination is to purify metals. It helps to remove volatile impurities. It also removes moisture. It can convert metal carbonates into oxides. 10. Haematite is called ore. Haematite is called ore because it has very high concentration of iron and can be used to extract iron on an industrial scale. 3 STEPS 3 STEPS EXERCISE EXERCISE STEP1 1. Choose the best answer from the given alternatives. a. What is the main character of a metal? i. they are good conductors of heat and electricity. ii. they are malleable and ductile. iii. they lose electrons to form positive ions. iv. they gain electrons to form negative ions. b. Gold does not have ore, why? i. Its ore is alluvial soil. ii. It is heavy so it does not form ores. iii. It is the least reactive, so it does not form a compound. iv. It is yellow and shiny, so it is found in elemental form. c. Which processes does smelting belong to? i. refining ii. grinding iii. oxidation iv. reduction d. What is used as an anode during the purification of silver by electro-refining? i. pure silver ii. silver ore iii. silver salt iv. impure salt e. Which technology is used for refining metals? i. amalgamation ii. electroplating iii. electrorefining iv. galvanization

412 metalS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur f. What are the sources of metals called? i. minerals ii. rocks iii. soil iv. ores 2. Define the following terms with required examples. a. Metals b. Ores c. Minerals d. Metallurgy e. Calcination f. Roasting g. Froth floatation h. Gravity separation i. Magnetic separation j. Smelting 3. Answer the following questions in very short. a. Which metal is obtained from magnetite and haematite? b. Name the chief ores of aluminium. c. Name the chief ores of copper. d. Name any two ores of silver. e. Which metal is found in elemental form? f. Where is gold found in nature? g. Name the metal that can be obtained from the given ores: i) Argentite ii) Limonite iii) Bauxite iv) Haematite h. Which ores are roasted to oxidize? k. Which metals can be extracted from magnetite and chalcopyrite? l. Which metallurgical step is the first one to purify ore? m. Which metal is extracted from siderite? STEP2 4. Give reasons. a. Iron is used for making cooking utensils. b. Aluminium is used for making body parts of aeroplanes. c. Copper is used for making electric wires. d. Gold is called an inert metal. e. Gold and silver are used for making ornaments. f. Aluminium tools are not affected by air and water. g. Aluminium is a very reactive metal. However, the foods in aluminium pots don’t react with the pots. h. Some minerals are not ores but all ores are minerals. i. Some ores are roasted after concentration.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 413 5. Differentiate between the following. a. Calcination and roasting b. Gravity separation and magnetic separation c. Ores and minerals 6. Answer the following questions in short. a. Write any two physical properties each of iron, aluminium, silver and copper. b. State any two properties of copper that make it suitable for making pots and pans. c. Write any three uses of each iron, aluminium, silver and copper. d. Describe the metallurgical steps in very short. STEP3 7. Answer the following questions. a. Write down the electric configuration of iron and mention the position of iron in the modern periodic table. b. Arrange aluminium, iron, gold, silver and copper in the increasing order of their melting points and boiling points. c. Write a brief note on the concentration of ores. Describe each method. d. Describe the electrorefining of copper.

414 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Key terms and terminologies of the unit 1. Hydrocarbons : Compounds which are formed by the combination of carbon and hydrogen are called hydrocarbons. 2. Organic compounds: The compounds formed by reaction of carbon with elements like hydrogen, oxygen, nitrogen, etc. are called organic compounds. 3. Inorganic compounds: The compounds which are derived from minerals are called inorganic compounds. 4. Saturated hydrocarbons : The hydrocarbons in which carbon atoms are connected by a single covalent bond are called saturated hydrocarbons. 5. Unsaturated hydrocarbons: The hydrocarbons in which carbon atoms are connected by a multiple (either double or triple) covalent bond are called unsaturated hydrocarbons. 6. Alkanes : The saturated hydrocarbons in which any two carbon atoms are connected by a single covalent bond are called alkanes. 7. Alkenes : The unsaturated hydrocarbons in which any two carbon atoms are connected by a double covalent bond are called alkenes. Sequence of Curriculum Issued by CDC  Introduction to hydrocarbons  Saturated and unsaturated hydrocarbon  IUPAC names and structural formula of the first four alkanes (methane, ethane, propane and n-butane)  Uses of methane, ethane, propane and n-butane  Introduction to alcohol  Functional group (hydroxide)  Types and examples of alcohol based on the number of hydroxide functional groups  Structural formula and uses of methanol, ethanol, glycol and glycerol. UNIT Hydrocarbon and Its Compounds 18 Estimated teaching periods Theory Practical 5 1 Friedrich Wohler is well known for obtaining beryllium in pure metallic form. He was born in the Roman empireon 31st July 1800 and died on 23rd September 1882. He was a German chemist and an expert on biochemistry and organic chemistry. He is also known for isomerism, Wohler synthesis and the Wohler process. He was the first to synthesise the organic compound urea. He was honoured with Copley Medal in 1872. Friedrich Wohler About the Scientist

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 415 8. Alkynes : The unsaturated hydrocarbons in which any two carbon atoms are connected by a triple covalent bond are called alkynes. 9. IUPAC : The full form of IUPAC is International Union of Pure and Applied Chemistry. 10. Functional group : A functional group is an atom or group of atoms that determine the chemical properties of a hydrocarbon. 11. Homologous series : A homologous series is a group of organic compounds having similar structures and chemical properties in which the successive compounds differ by -CH2 group. 12. Isomers : Isomers are organic compounds having the same molecular formula but different structures and properties. 13. Isomerism : Isomerism is the existence of two or more different organic compounds having the same molecular formula but different structures and properties. 14. Alcohol : Alcohol is an organic compound which contains hydroxyl group (OH). 15. Monohydric alcohol: Alcohol having only one hydroxyl group (-OH) is called monohydric alcohol. 16. Dihydric alcohol : Alcohol having two hydroxyl groups (–OH) in one compound is called dihydric alcohol. 17. Trihydric alcohol : Alcohol having three hydroxyl groups in one compound is called trihydric alcohol. 18. Glycerol : Glycerol is formed by the replacement of three hydrogen atoms from three carbons of propane by three hydroxyl groups. Glycerol is a colourless liquid having a sweet taste. 19. Glycol: Glycol is a colorless, odourless, flamable viscous liquid having a sweet taste. Introduction Carbon is one of the most important and unique non-metallic elements. The word carbon has been derived from the Latin word 'carbo', which means soot or charcoal. Carbon is widely distributed on the earth in free as well as in combined state. In free state, it is present in diamond, graphite, charcoal, coal, etc. whereas in combined state, it is present in carbon monoxide, carbon dioxide, carbonates, carbohydrates, proteins, fats, nucleic acids, petroleum, natural gas, etc. The bodies of living beings contain carbon and its compounds in abundant quantity. When we burn these carbon containing compounds, we get black soot, smoke, charcoal, etc. Organic and Inorganic Compounds In ancient time, scientists believed that organic compounds are produced within the body of living beings by the natural process. They also believed that formation of organic compounds takes place under the influence of vital force and they cannot be prepared in laboratory. But in 1828 AD, German chemist Friedrich Wohler synthesized urea in the laboratory by heating ammonium cyanate. Ammonium cyanate is an inorganic compound whereas urea is an organic compound. This experiment displaced the vital force theory of organic compounds. Thereafter many organic compounds were synthesized artificially in the laboratory. The compounds formed by reaction of carbon with elements like hydrogen, MEMORY TIPS There are certain compounds like CO3 and CO that contain carbon but are traditionally called inorganic compounds. Compounds like CaCO3, Na2CO3, etc. also contain carbon atom but they have electrovalent bond and they do not have hydrogen. So these compounds are called inorganic compounds.

416 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur oxygen, nitrogen, etc. are called organic compounds. Examples: Methane, ethane, propane, butane, alcohol, ether, glycerol, etc. The branch of chemistry in which we study about organic compounds is called organic chemistry. The compounds which are derived from minerals are called inorganic compounds. They contain other elements except hydrocarbon. For example, water, sodium chloride, calcium carbonate, hydrochloric acid, etc. The branch of chemistry in which we study about inorganic compounds is called inorganic chemistry. Hydrocarbons Compounds which are formed by the combination of carbon and hydrogen are called hydrocarbons. For example, methane (CH4 ), ethane (C2 H6 ), propane (C3 H8 ), ethene (C2 H4 ), ethyne (C2 H2 ), etc. These compounds are formed by bonding between carbon and hydrogen. So, they are called hydrocarbons. The main sources of hydrocarbons are petroleum and natural gas. Hydrocarbons are classified into two groups. They are: 1) Saturated hydrocarbons 2) Unsaturated hydrocarbons Project Work Using different local materials like toothpick, potatoes, tomatoes, grapes, etc. make different types of hydrocarbons. Saturated Hydrocarbons The hydrocarbons in which carbon atoms are connected by a single covalent bond are called saturated hydrocarbons. They are also called alkanes. For example, methane (CH4 ), ethane (C2 H6 ), propane (C3 H8 ), etc. The general formula of saturated hydrocarbons is CnH2n+2 where 'n' represents the number of carbon atoms. In an alkane, the suffix is 'ane'. Some more examples of alkanes with their molecular formula, structural formula and IUPAC name are given below: S.N. No. of carbon atoms Moleular formula Structural formula IUPAC name 1. 1 (Meth) CH4 H I H–C–H I H Methane 2. 2 (Eth) C2 H6 H H I I H – C – C – H I I H H Ethane 3. 3 (Prop) C3 H8 H H H I I I H–C–C–C–H I I I H H H Propane

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 417 4. 4 (But) C4 H10 H H H H I I I I H–C–C–C–C–H I I I I H H H H Butane 5. 5 (Pent) C5 H12 H H H H H I I I I I H–C–C–C–C–C–H I I I I I H H H H H Pentane 6. 6 (Hex) C6 H14 H H H H H H I I I I I I H–C–C–C–C–C–C–H I I I I I I H H H H H H Hexane 7. 7 (Hept) C7 H16 H H H H H H H I I I I I I I H–C–C–C–C–C–C–C–H I I I I I I I H H H H H H H Heptane 8. 8 (Oct) C8 H18 H H H H H H H H I I I I I I I I H–C–C–C–C–C–C–C–C–H I I I I I I I I H H H H H H H H Octane 9. 9 (Non) C9 H20 H H H H H H H H H I I I I I I I I I H–C–C–C–C–C–C–C–C–C–H I I I I I I I I I H H H H H H H H H Nonane 10. 10 (Dec) C10H22 H H H H H H H H H H I I I I I I I I I I H–C–C–C–C–C–C–C–C–C–C–H I I I I I I I I I I H H H H H H H H H H Decane Saturated hydrocarbons, i.e. alkanes are chemically less reactive. So, they are also called paraffins (para-less, affins-reactivity). Unsaturated Hydrocarbons The hydrocarbons in which carbon atoms are connected by a multiple (either double or triple) covalent bond are called unsaturated hydrocarbons. For example, ethene (C2 H4 ), propene (C3 H6 ), ethyne (C2 H2 ), propyne (C3 H4 ), etc. Unsaturated hydrocarbons are of two types. a) Alkenes b) Alkynes

418 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur a) Alkenes The unsaturated hydrocarbons in which any two carbon atoms are connected by a double covalent bond are called alkenes. The general formula of alkene is CnH2n where 'n' represents the number of carbon atoms. The suffix of alkenes is -ene. The molecular formula, structural formula and IUPAC name of some alkenes are iven below: S.N. No. of carbon atoms Molecular formula Structural formula IUPAC name 1. 2 (Eth) C2 H4 C = C H H H H Ethene 2. 3 (Prop) C3 H6 H–C–C = C H H H I I I H H Propene 3. 4 (But) C4 H8 H–C–C–C=C H H H I H I H I H I H I Butene 4. 5 (Pent) C5 H10 H–C–C–C–C=C H H H I H I H I H I H I H I H I Pentene 5. 6 (Hex) C6 H12 H H H–C–C–C–C–C=C H I H I H I H I H I H I H I H I H I Hexene 6. 7 (Hept) C7 H14 H H H–C–C–C–C–C–C=C H I H I H I H I H I H I H I H I H I H I H I Heptene 7. 8 (Oct) C8 H16 H H H–C–C–C–C–C–C–C =C H I H I H I H I H I H I H I H I H I H I H I H I H I Octene 8. 9 (Non) C9 H18 H H H–C–C–C–C–C–C–C–C=C H I H I H I H I H I H I H I H I H I H I H I H I H I H I H I Nonene 9. 10 (Dec) C10H20 H H H–C–C–C–C–C–C–C–C–C=C H I H I H I H I H I H I H I H I H I H I H I H I H I H I H I H I H I Decene Alkenes are also called olefins because they react with chlorine and produce oil-like substances.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 419 b) Alkynes The unsaturated hydrocarbons in which any two carbon atoms are connected by a triple covalent bond are called alkynes. The general formula of alkyne is CnH2n-2. The suffix of alkynes is '-yne'. The molecular formula, structural formula and IUPAC name of some alkynes are given below: S.N. No. of carbon atoms Molecular formula Structure IUPAC name 1. 2 (Eth) C2 H2 H–C ≡ C–H Ethyne 2. 3 (Prop) C3 H4 H – C–C ≡ C – H H I I H Propyne 3. 4 (But) C4 H6 H – C–C–C ≡ C – H H I H I I H I H Butyne 4. 5 (Pent) C5 H8 H – C– C– C– C ≡ C – H H I H I I H I H H I I H Pentyne 5. 6(Hex) C6 H10 H – C–C– C– C– C ≡ C – H H I H I I H I H H I H I I H I H Hexyne 6. 7 (Hept) C7 H12 H – C–C–C–C–C–C ≡ C – H H I H I I H I H H I H I I H I H H I I H Heptyne 7. 8 (Oct) C8 H14 H – C–C–C–C–C–C–C ≡ C – H H I H I I H I H H I H I I H I H H I H I I H I H Octyne

420 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur 8. 9 (Non) C9 H16 H – C–C–C–C–C–C–C–C ≡ C–H H I H I I H I H H I H I I H I H H I H I H I I H I H I H Nonyne 9. 10 (Dec) C10H18 H – C–C–C–C–C–C–C–C–C ≡ C–H H I H I I H I H H I H I I H I H H I H I H I H I I H I H I H I H Decyne IUPAC System The full form of IUPAC is International Union of Pure and Applied Chemistry. This system has been introduced by scientists to bring uniformity in naming organic and inorganic compounds. In this system, one compound has only one name to avoid errors in understanding a particular compound. The process of naming hydrocarbons in the IUPAC system is given below: i. The number of carbon atoms in a hydrocarbon is indicated by using the given stems: One carbon atom is indicated by writing 'Meth', two carbon atoms by 'Eth', three by 'Prop', four by 'But', five by 'Pent', six by 'Hex', seven by 'Hept', eight by 'Oct', nine by 'Non' and ten carbon atoms are indicated by writing 'Dec'. ii. A saturated hydrocarbon containing single bond between carbon atoms is indicated by writing '-ane' after the stem. iii. An unsaturated hydrocarbon containing a double covalent bond is indicated by writing '-ene' after the stem. iv. An unsaturated hydrocarbon containing a triple covalent bond is indicated by writing '-yne' after the stem. For example: (i) H – C – C – C – H H I H I I H I H H I I H No. of carbon atoms = 3 ∴ Stem = Prop Type of bond = single covalent = ane ∴ The name of the given hydrocarbon = Prop + ane = Propane (i) H – C = C – C – C – H I H I H H I H I I H I H

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 421 No. of carbon atoms = 4 ∴ Stem = But Type of bond = Double covalent = ene ∴ The name of the given hydrocarbon = But + ene = Butene Functional Group A functional group is an atom or group of atoms that determine the chemical properties of a hydrocarbon. For example, hydroxyl (– OH), ether ( – O –), aldehyde (– CHO), etc. Some functional groups with their symbol, structure and compounds are given below: S.N. Name of functional group Symbol Structure Organic compounds 1. Hydroxyl –OH – OH Alcohol 2. Carboxylic acid –COOH O II – C – OH Acid 3. Ether –O– –O– Ether 4. Aldehyde –CHO O II – C – H Aldehyde 5. Keto –CO– O II – C – Ketone 6. Amino –NH2 H I – N – H Amine Alkyl Radical The group of atoms formed by removing one hydrogen from an alkane is called alkyl radical. Its general formula is CnH2n+1. For example, methyl (CH3 + ) radical is formed by removing one hydrogen atom from methane (CH4 ). Similarly, ethyl (C2 H5 + ) radical is formed by removing one hydrogen atom from ethane (C2 H6 ), etc. Homologous Series A homologous series is a group of organic compounds having similar structures and chemical properties in which the successive compounds differ by -CH2 group. All the members of a

422 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur homologous series can be represented by the same general formula, and they can be prepared by similar methods. For example, The first five members of the homologous series of alkanes are given below: Common name Molecular formula (CnH2n+2) Structural formula Condensed formula Methane CH4 H – C – H H I I H CH4 Ethane C2 H6 H – C – C – H H I H I I H I H CH3 CH3 Propane C3 H8 H – C – C – C – H H I H I H I I H I H I H CH3 CH2 CH3 Butane C4 H10 H – C – C – C – C – H H I H I H I H I I H I H I H I H CH3 CH2 CH2 CH3 Pentane C5 H12 H – C – C – C – C – C – H H I H I H I H I H I I H I H I H I H I H CH3 CH2 CH2 CH2 CH3 Some Important Organic Compounds and Their Uses a) Methane (CH4) Methane is the first member of hydrocarbons. It is the simplest aliphatic hydrocarbon. It occurs in gaseous state at room temperature. Methane is also called marsh gas because it is formed by the decomposition of organic matter within water in marshy places. Methane is found in natural gas, petroleum, coal minesnd biogas.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 423 Methane H – C – H H I I H Methane Uses of methane i. It is used as a fuel in the form of LNG (liquified natural gas). ii. It is used in the manufacture of hydrogen (H2 ), chloroform (CHCl3 ), formaldehyde (HCHO), carbon tetrachloride (CCl4 ), methyl alcohol (CH3 OH), etc. iii. It is used to make carbon black which is used in rubber industries. iv. It is used to make printing ink and paints. b. Ehane (C2H6) Ethane is the second member of alkane series. It is a saturated hydrocarbon. It occurs in natural gas and petroleum mines. Uses of ethane i. It is used as a source of heat for cooking purpose in the form of biogas. ii. It is used for making shoe polish, printers' ink, ethanol, diethyl ether, etc. c. Propane (C3H8) Propane is the third member of alkane series. It is a saturated hydrocarbon which occurs in natural gas and petroleum mines. Propane is a highly inflmable gas. H – C – C – C – H H I H I H I I H I H I H Propane Propane Uses of propane i. It is used as a fuel in lighters. ii. It is used in petroleum industries for cooling purpose. d. Butane (C4H10) Butane is the fourth member of alkane series. It is a saturated hydrocarbon which occurs in petroeum mines. MEMORY TIPS Methane is also called marsh gas as it is found in marshy places. H – C – C – H H I H I I H I H Ethane Ethane MEMORY TIPS Propane (C3H8) is highly inflammable. So, it is used as a fuel in lighters.

424 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur H – C – C – C – C – H H I H I H I H I I H I H I H I H Butane Butane Uses of butane i. Butane is used as a source of heat in the form of LP gas as this gas liquefies easily under pressure. ii. It is used in rubber industries as a raw material. Isomers and Isomerism Isomers are organic compounds having the same molecular formula but different structure and properties. Isomerism is the existence of two or more different organic compounds having the same molecular formula but different structures and properties. Isomerism is possible only with hydrocarbons having four or more carbon atoms. For example, n-Butane and iso-butane are two isomer of butane. Name Molecular formula Structural formula Condensed formula i) n - Butane C4 H10 H – C – C – C – C – H H I H I H I H I I H I H I H I H CH3 –CH2 –CH2 –CH3 ii) iso-Butane C4 H10 H – C – C – C – H H I H I H I H – C – H I I H I H I H CH3 I CH3 – CH – CH3 Alcohol Alcohol is an organic compound which contains hydroxyl group (OH). Alcohols are derivatives of alkanes because they are formed by substitution of hydrogen atom of an alkane by hydroxyl group. or example, H I H I I H I H H – C – H H – C – OH –H +OH Methyl alcohol or methanol

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 425 Types of Alcohol Depending on the number of hydroxyl groups, there are different types of alcohol. But in this unit, we study three types of alcohol: a. Monohydric alcohol Alcohol having only one hydroxyl group (-OH) is called monohydric alcohol. It is formed by the replacement of one hydrogen atom of an alkane by one hydroxyl group. Frexample, H I H I H I H I H I H I I H I H I H I H I H I H H – C – H H – C – C – H H – C – C – OH H – C – OH –H +OH –H +OH (Methane) (Methyl alcohol or methanol) (Ethane) (Ethyl alcohol or ethanol) FACTS WITH REASONS Why is methyl alcohol called monohydric alcohol? Methyl alchol consists of only one hydroxyl group (-OH). So, it is called monohydric alcohol. Why is glycerol called trihydric alcohol? Glycerol consists of three hydroxyl (OH) groups. So, it is called a trihydric alcohol. b. Dihydric alcohol Alcohol having two hydroxyl groups (–OH) in one compound is called dihydric alcohol. It is formed by the replacement of two hydrogen atoms from two carbons of ethane by two hydroxyl groups. or example, H I H I H I H I I H I OH I OH I H H – C – C – H H – C – C – H –2H +2OH (Ethane) (Ethylene glycol)

426 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur c. Trihydric alcohol Alcohol having three hydroxyl groups in one compound is called trihydric alcohol. It is formed by the replacement of three hydrogen atoms from three carbons of propane by three hydroxyl groups. Fr example, H I H I H I H I H I H I I H I OH I OH I OH I H I H H – C – C – C – H H –C – C – C – H –3H +3OH (Propane) (Glycerol) Some Important Alcohols a. Methyl alcohol or Methanol (CH3– OH) It is the first member of monohydric alcohol which is formed by the replacement of one hydrogen from methane by one hydoxyl group. (Methanol) (Methane) (Methanol) –H +OH H I H I H I I H I H I H H – C – OH H – C – H H – C – OH Uses of methyl alcohol i. Methyl alcohol is used as fuel because it produces a large amount of heat without smoke. So, it is used in a spirit lamp. ii. It is used to manufacture perfumes, dyes, paints, synthetic fibre, etc. iii. It is used to dissolve fats, oil, paints, varnish, etc. iv. It is used to make different types of compounds like methyl chloride, formaldehyde, etc. b. Ethyl alcohol or Ethanol (C2H5OH) It is the second member of monohydric alcohol which is formed by the replacement of one hydrogen from ethane by one hydroxyl group. It is commonly known s alcohol. (Ethanol) H I H I I H I H H – C – C – OH (Ethane) (Ethanol) H I H I H I H I I H I H I H I H H – C – C – H –H H – C – C – OH +OH

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 427 Uses of Ethyl alcohol i. Ethyl alcohol is used in alcoholic beverages for drinking purpose. ii. It is used in thermometer as a thermometric liquid. iii. It is used as a fuel. iv. It is used to make medicines, paint, soap, synthetic rubber, etc. v. It is used to dissolve fat, oil, paints, resin, etc. vi. It is used in hospitals to clean wounds and utensils. vii. It is used as laboratory reagent to make various compounds like ether, chloroform, iodoform, etc. c. Glycol (Dihydric alcohol or ethylene glycol or ethane 1, 2 diol) Glycol or ethylene glycol is formed by the replacement of two hydrogen atoms from two carbons of ethane by two hydroxyl groups. Glycol is a colorless, odourless, flamable viscous liquid having a sweet taste. It is poisonous in high conetration. (Ethane) (Glycol) H I H I H I H I I OH I OH I H I H H–C–C–H H–C–C–H –2H +2OH H I H I I OH I OH C2 H4 (OH)2 H – C – C – H CH2 OH – CH2 OH (Molecular formula) (Condensed formula) (Structural formula) Glycol Uses of glycol i. Glycol is used as an industrial compound to manufacture polyester fibre. ii. It is used as an anti-freeze liquid in cooling system of the engine. iii. It is used in the preparation of printing inks, ballpoint pens, stamp-pad inks, solvents, paints, plastics, films, cosmetics, etc. d. Glycerol (Trihydric alcohol or Propane 1, 2, 3 triol) The word glycerol is derived from "glyceros" which means sweet. It is formed by the replacement of three hydrogen atoms from three carbons of propane by three hydroxyl groups. Glycerol is a colorless liquid having a sweet taste. It dissolves in water but ntin ether. (Propane) (Glycerol) H I H I H I H I H I H I I H I OH I OH I OH I H I H H–C–C–C–H H–C–C–C–H –3H +3OH MEMORY TIPS Ethyl alcohol, or ethanol, is used in alcoholic drinks.

428 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur H I H I H I I OH I OH I OH C3 H5 (OH)3 H – C – C – C – H CH2 OH – CHOH – CH2 OH (Molecular formula) (Condensed formula) (Structural formula) Glycerol Use of glycerol i. Glycerol is used as a sweetening agent in confectionery, beverages and medicines. ii. It is used in the manufacture of soaps and cosmetics of good quality. iii. It is used for the preservation of fruits and tobacco. iv. It is used in the preparation of printing inks and stamp-pad inks. v. It is used in lip guards, face creams, etc. to protect the skin frombeing dry. HOT SKILL HIGHER ORDER THINKING SKILL 1. Arya has dry lips and dry skin. Which hydrocarbon should she use to treat dry lips and dry skin? Write the molecular formula and structural formula of the compound. Since Arya has dry lips and dry skin, she should use a hydrocarbon called glycerol. The molecular formula of glycerol is C3 H5 (OH)3 . The structural formula of glycerol is H I H I H I I OH I OH I OH H – C – C – C – H 2. Sugar is non-electrolyte. Sugar is an organic compound. It has a covalent bond between carbon atoms and hydrogen atoms. It does not ionize in water. So, it cannot pass electricity in solution. So, sugar is a non-electrolyte. 3. Compare between glycol and ethanol. Differences between glycol and ethanol are listed below: SN Ethyl glycol SN Ethanol 1 Glycol contains two hydroxyls groups each of two carbon. 1 Ethanol contains one hydroxyl group in one carbon. 2 Glycol is more toxic for humans. 2 Ethanol is less toxic for humans. MEMORY TIPS 1. The word glycerol has been derived from the Greek word glyceros which means 'sweet' in taste. 2. The IUPAC name of glycerol is propane 1, 2, 3 triol.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 429 4. Write the name of the hydrocarbon shown below. What is formed when we replace one hydrogen from the first carbon atom with a hydroxyl functional group? H I H I H I I H I H I H H – C – C – C – H The hydrocarbon shown in the picture is propane. If we replace one hydrogen atom with the first carbon atom, propanol will be formed. H I H I H I I H I H I H H – C – C – C – H - H + OH H I H I H I I H I H I H H – C – C – C – OH 5. Write any two differences between paraffin and olefin. The differences between paraffin and olefins are: SN Paraffin SN Olefin 1 Paraffin is a saturated hydrocarbon. 1 Olefins are unsaturated hydrocarbons. 2 Paraffin is less reactive. Examples: alkanes 2 Olefins are more reactive. Examples: alkenes and alkynes 6. Ethylene is called unsaturated hydrocarbon. Ethylene is called unsaturated hydrocarbon because there is a double covalent bond between two carbon atoms(CH2 =CH2 ). One of that double bonds can be easily broken whenever sufficient hydrogen is available. 7. Glycerol is called trihydric alcohol. Glycerol is called trihydric alcohol because it contains three hydroxyl functional groups. One hydroxyl radical in each carbon. 8. Why is methanol used as a source of fuel for spirit lamps? Methanol is used as a source of fuel for spirit lamps because it burns with oxygen to produce a large amount of heat. 9. The hydroxyl radical (-OH) is called a functional group. The hydroxyl radical (-OH) is called a functional group because it can combine with alkyl radicals and change their properties. 10. Mention the bond exists between carbon and hydrogen in propene. Write its structural formula. Why is the bond between carbon and carbon weaker than the bond between carbon and hydrogen? The covalent bond exists between carbon and hydrogen in propene. The structural formula of propene is H H H C C C H H H Hydrogen is small in size than carbon. If atoms are small, bonds will be shorter. Shorter bonds will be stronger. The bond between carbon and carbon is longer than the bond between carbon and hydrogen. So, the bond between two carbon atoms is weaker than the bond between carbon and hydrogen.

430 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur 3 STEPS 3 STEPS EXERCISE EXERCISE STEP1 1. Choose the best answer from the given alternatives. a. Why is ethane less reactive than ethene? i. ethane is smaller than ethene. ii. ethane has less melting point than ethene iii. ethane has one but ethene has two covalent bonds between carbon atoms. iv. ethane is unsaturated but ethene is saturated. b. Which of the following is ethylene? i. H2 C=CH2 ii. CH3 -CH3 iii. HC≡CH iv. CH3 CH2 CH₃ c. Which one of the following is used as coolant? i. butane ii. glycol iii. ethanol iv. glycerol d. What is represented by -OH? i. oxygen and hydrogen atom ii. Hydroxyl group iii. ether iv. Hydroxide ion e. What is glycerine? i. alkane ii. alcohol iii. ether iv. ethene f. Which one of the following hydrocarbons belongs to the alkane series? i. ethyl glycol ii. n-butane iii. acetylene iv. methanol 2. Define the following terms with required examples. a. Hydrocarbon b. Saturated hydrocarbon c. Unsaturated hydrocarbon d. Homologous series e. Alkane f. Alkene g. Alkyne h. Functional group i. Alcohol j. Monohydric alcohol k. Dihydric alcohol l. Trihydric alcohol m. Isomer n. Isomerism

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 431 o. Glycol p. Glycerol q. Paraffin r. Olefin s. Alkyl radical 3. Answer the following questions in very short. a. Give any two examples of hydrocarbons. b. How many types of hydrocarbons are there? Name them. c. What is the full form of IUPAC? d. Where is methane found? e. Where is propane gas found in nature? f. Write the full form of L.P.G. g. Which alcohol is used to manufacture formaldehyde? h. What is the molecular formula of methyl alcohol? i. Write the molecular formula of hydrocarbon used as a beverage. j. Which hydrocarbon is used in the spirit lamp? Write its name and molecular formula. k. Mention types of alcohol based on the number of the hydroxyl group. m. What is represented by CnH2n+2? STEP2 4. Give reasons. a. Methane is called a hydrocarbon. b. Butane is called a saturated hydrocarbon. c. Propene is called an unsaturated hydrocarbon d. Methane is called marsh gas. e. Propane is used as a fuel in lighters. f. Glycerol is used in sweets. g. Ethyl alcohol is used to make Dettol. h. Ethane is called paraffin but ethene is called olefin. 5. Differentiate between the following. a. Saturated hydrocarbon and unsaturated hydrocarbon b. Propane and propene c. Glycol and glycerol 6. Answer the following questions in short. a. Write the molecular formula of glycerol with its two properties.

432 HydRocaRBon and itS comPoundS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur b. What type of hydrocarbons are called paraffin? c. Acetylene is an unsaturated hydrocarbon. Write down its reason based on its structural formula. d. Write down the structural formula and one use of ethane. e. Write any three uses each of methyl alcohol and ethyl alcohol. f. Write any three uses of glycerol. g. Write the structural formula of the compound formed by replacing a hydrogen atom with an -OH group from ethane. h. Write any three uses of methane gas. i. Write the molecular and structural formula of the following: ethylene, ethyl alcohol, glycerol, methane, ethanol, butane, propane, acetylene, ethene, ethane, propyne and methyl alcohol. j. Which hydrocarbon should we use to avoid dry skin or heal them? Write the molecular formula and structural formula of the compound. 7. Identify the given compounds and write anyone use of each: H H H C OH H C OH H C OH H H C OH H C OH OH H H C OH OH STEP3 8. Answer the following questions. a. Write any three uses of methane gas. b. Mention the method of naming hydrocarbons. c. Write the name of the compound and its structural formula which is formed by the displacement of three hydrogen atoms with three hydroxide radicals from propane through various chemical reactions. d. Write the name and structural formula of the compound which is formed by connecting ethane to hydroxyl radical. Give one example of trihydric alcohol and also mention its structural formula. e. Give the structural formula of Glycol and write with reasons if it is saturated or not.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 433 f. Write down the structural formula of the alkyne having three carbon atoms. Name the hydrocarbon formed by reacting the above hydrocarbon with sufficient hydrogen. Also, write one use of the newly formed hydrocarbon. g. A certain hydrocarbon has a structural formula as shown in the diagram. Answer the following questions after observing the structural formula. i. Is this saturated hydrocarbon or unsaturated hydrocarbon? ii. If the above-mentioned hydrocarbon gets plenty of hydrogen, a new hydrocarbon will be formed. Name and draw the structural formula of that hydrocarbon. h. What are the compounds having the following structural formula? Write the types of hydrocarbons based on the bond. H H H C H H C H H C H H C H H C H (a) (b) (c) H-C≡ C- H H H C OH C C C

434 cHemicalS uSed in daily life Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Key terms and terminologies of the unit 1. Food preservation : The process by which food materials are protected from spoilage is called food preservation. 2. Food preservatives : The materials or chemical substances that can be added to food to prevent spoilage are called food preservatives. 3. First class food preservatives : First class food preservatives are those which can be used in any amount without exact measuring. 4. Second class food preservatives: Second class food preservatives are those which must be used in exact amount as they are prescribed. 5. Traditional food preservatives : The spices, oils, salts, sugar, chilli, etc. that are used for ages to preserve food are called traditional food preservatives. 6. Chemical food preservatives : The group of man-made chemical substances added to food or sprayed to prevent spoilage is called chemical or synthetic food preservatives. 7. Induced ripening agents : Those chemical substances which are used to ripen fruits in short period of time are called induced ripening agents. 8. Calcium carbide : Calcium carbide is a white chemical compound with the chemical formula CaC2 . It can be used to artificially ripen fruit. Sequence of Curriculum Issued by CDC  Introduction, importance and adverse effects of food preservatives  Introduction, importance and adverse effects of chemicals used for cleaning  Precautions while storing and using insecticides, pesticides, rodenticides, acid and chlorine  Chemical pollution and its management  Chemical pollution from cement, glasses, ceramics, plastics, fibre, chemical fertilizer, soap and detergent. Management of chemical pollution. UNIT Chemicals Used in Daily Life 19 Estimated teaching periods Theory Practical 5 1 Nicolas Appert is well known as the father of food science. He was born in France on 17th November 1749 and died on 1st June 1841. He was a French inventor of airtight food preservation. He developed a canning process (storing food in a glass jar, sealed with wax and cork then boiling) to store food such as soups, vegetables, dairy products, jellies and jamson an industrial scale. Nicolas Appert About the Scientist

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 435 9. Antioxidants : The chemical substances that are mixed in the food to prevent oxidation are called antioxidants. 10. Pesticides : Pesticides are those chemical substances which are used to kill or chase insects, rodents, termites, fungi, etc. 11. Biodegradable pesticides : Biodegradable pesticides are those pesticides that are broken down into harmless compounds by microbes, bacteria and fungi. 12. Non-biodegradable pesticides: Non-biodegradable pesticides are those that are usually stable and do not decompose. 13. Insecticides : The toxic chemical substances that are usually used to kill or chase or disturb the reproduction of insects are called insecticides. 14. Herbicides : Herbicides are poisonous chemicals that are usually used to kill undesired plants. 15. Rodenticides : The toxic substances which are used to get rid of rodents are called rodenticides. 16. Bactericides : The poisonous chemicals used for killing or preventing the reproduction of bacteria are called bactericides. 17. Fungicides : Those chemical compounds that are used for killing fungi are called fungicides. 18. Larvicides : The poisonous chemical substances that are usually made to kill larva of insects are called larvicides. 19. Miticides : The chemicals used to get rid of mites and ticks are called miticides. 20. Contact pesticides : The chemical compounds that can kill insects, herbs, larvae, etc. that come in direct contact are called contact pesticides. 21. Systemic pesticides : Systemic pesticides are toxic chemicals that are absorbed by the body of an organism and distributed all over the body by the transportation system. 22. Stomach pesticides : The toxic chemicals that must enter the body through the mouth into the digestive system are called stomach pesticides. 23. Fumigants : The fumigants are those toxic chemicals that change into gas when exposed to moist air and kill the animals if inhaled. 24. Cleansing agents : The chemical substances which are used to remove dust, dirt, germs, foul smell, stains, etc. are called cleansing agents. 25. Synthetic cleaners : Soap, shampoo, detergents, sanitizer, stain remover, etc. are man-made synthetic cleaners. 26. Traditional cleaner : Reetha, Amla, Shikakai, wooden ash, lemon juice, clay, etc. which are used for cleaning purpose are called traditional cleansing agents. 27. Soap : Chemically soap is a sodium salt of higher fatty acid that has cleansing property in water. 28. Detergents : Detergents are sodium salts of long chain benzene sulphonic acid, which are mostly non- biodegradable with more cleansing property. 29. Chemical pollution : The pollution created by unwanted and excessive use of chemical substances is called chemical pollution. Introduction In our surroundings, there are various types of chemical substances, which may be natural or man-made. These substances are used by human beings to fulfil their basic needs of food, shelter, clothing and health. In ancient times, only natural substances were there, and men used these substances to meet their requirements. But now with the development of science

436 cHemicalS uSed in daily life Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur and human knowledge, a large number of chemical substances like food preservatives, antioxidants, acids, chlorine, calcium carbide, synthetic cleaners, soaps, detergents, medicines, fertilizers, pesticides, fungicides, rodenticides etc. are made by humans. By the use of those natural as well as man-made chemical substances, we are making our lives easier, more comfortable and more luxurious. Fig: detergent Fig: synthetic cleaners Fig: food additives Fig: food preservation Fig: chlorine Food preservatives The foods are organic substances. They are perishable. Most of the food contains moisture. Rice, grains, fruits, meat etc. are usually spoilt by bacteria, fungi and moisture. When the food is spoilt, it is unfit for consumption. If we eat spoilt foods, we become sick. People are using various techniques to preserve food materials. The process by which food materials are protected from spoilage is called food preservation. Traditionally food is preserved by adding salts, sugars, spices, dehydration, pickling and controlled fermentation. Nowadays refrigerators, canning, boiling and adding synthetic chemical preservatives are common to preserve food. The materials or chemical substances that can be added to food to prevent spoilage are called food preservatives. Food preservatives are used since prehistoric times. FACTS WITH REASONS Canned food does not contain preservatives. Canned food does not contain preservatives because the germs are already killed by heating before packaging them in air tight container. ACTIVITY 1 Visit your grandparents. Try to find out how they store vegetables for winter when there were no refrigerators. First class preservatives First class food preservatives are those which can be used in any amount without exact measuring. For example, salt, sugar, oil, etc. Second class preservatives Second class food preservatives are those which must be used in exact amount as they are prescribed. For example, sodium or potassium nitrate, benzoic acid and their salt, sulphur dioxide, etc. MEMORY TIPS There are a lot of preservatives in processed foods. So we should prefer fresh food.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 437 Traditional food preservatives Food can be preserved by adding certain spices, salts, sugar and oil. Traditionally Nepalese people are also using various substances to preserve food. The spices, oils, salts, sugar, chilli, etc. that are used for ages to preserve food are called traditional food preservatives. For example, Nepalese people usually cut vegetables such as radish and dry them in the sunlight. Then these vegetables are mixed with spicy ingredients such as garlic, ginger, turmeric, Himalayan salt, hot chilli and mustard oil. Since these ingredients naturally kill bacteria, food won’t spoil for a very long time. A properly preserved vegetable by this method will last for almost a year. Fig: pickled radish Fig: pickled mushroom Fig: pickled of cauliflower Nepalese also preserve meat by using natural fat, oil, turmeric etc. They cut meat into tiny long pieces. A paste of turmeric, garlic etc. is polished on the meat. Mustard oil or fat is used on the meat. Then it is smoked and dried in the sun for many days. The meat will be preserved for months. Figure of oiled, smoked and then dried meat Farmers also add leaves of plants such as titepate, neem, neem oil,timur, aashuro, etc. on grains such as paddy, wheat and mustard before storing. It helps to repel harmful insects such as wheat weevil (ghun) and moths. It preserves food for many months. Lemon, vinegar, honey and sugar can also be used to preserve food because of their antimicrobial properties. FACTS WITH REASONS Plenty of mustard oil is used while making pickles from dried radishes. Plenty of mustard oil is used while making pickles from dried radish because oil blends with other spices, remove moisture, controls bacterial growth, and reduces fungal activities. As a result, food won’t spoil. MEMORY TIPS Seeds are dried and stored in a pot. The mouth of the pot is covered with a thick layer of firewood ash to prevent the entry of bacteria, fungus, moths, spores and wheat weevil.

438 cHemicalS uSed in daily life Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur ACTIVITY 2 Cut radish into tiny slices and dry them in sunlight for a few days. Mix turmeric powder, salt, mustard seeds, chilli and boiled mustard oil. Pack it in an airtight plastic container and keep it in the sunshine frequently for a week. Will the food last for one month? Observe. Synthetic or chemical food preservatives Besides traditional food preservatives, various other chemical substances can be used to preserve food. Especially food companies use varieties of artificial food preservatives to preserve foods. Such preservatives prevent spoilage, discolouration and contamination. The group of man-made chemical substances added to food or sprayed to prevent spoilage is called chemical or synthetic food preservatives. These preservatives kill bacteria, yeast and other microbes. It also prevents oxidation. So, the food can remain fresh for a longer time. Some of the synthetic food preservatives are organic and some are inorganic. Some examples of chemical food preservatives are sodium benzoate sorbate, sulphur dioxide, nitrates and nitrites, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), calcium propionate, sodium metasulphite, etc. Figure of bakery items, breads, processed meat etc. that can possibly contain synthetic preservatives Importance of synthetic food preservatives i. They help to prevent or slow down the spoilage from bacteria, fungi and micro-organisms. ii. Since they kill microbes, they decrease the chance of food-borne diseases. iii. They preserve the freshness, colour, flavour and texture of the food. iv. Since food can be stored for a longer duration, they can be transported to various places. Adverse effects of synthetic food preservatives i. Some synthetic food preservatives can cause deadly allergies in some people. ii. They can cause diarrhoea, abdominal pain and low blood pressure in some people. iii. Benzoates can increase the chance of blood cancer. iv. They can increase the chance of cancer. FACTS WITH REASONS Processed and packaged food such as yoghurt, sauce and bread contain synthetic food preservatives. Why? Processed and packaged food such as yoghurt, sauce and bread contain synthetic food preservatives to kill microbes, bacteria and moulds that help to prevent food spoilage. MEMORY TIPS For food manufacturers, artificial preservatives bring in a lot of benefits for them because they keep the product longer, more eye-catching and more attractive, and last longer.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 439 ACTIVITY 3 If you have any processed food, try to find out what preservatives they have used. Most of the time they do not mention it. Food preservatives for induced fruits ripening Those chemical substances which are used to ripen fruits in short period of time are called induced ripening agents. For example, calcium carbide, ethylene gas, ethephon, etc. Artificial ripening helps to ripen fruits faster. Traditionally we ripen fruits covering them by thick jute bags, cotton bags, blanket, etc. But, now a days different types of synthetic chemical substances are used to do it. The most popular chemical ripening agent is calcium carbide. Calcium carbide Calcium carbide is a white chemical compound with the chemical formula CaC2 . It can be used to artificially ripen fruit. Calcium carbide reacts with the moisture present in the fruits and produces acetylene gas. The acetylene gas helps in the ripening of fruits. Artificial ripening helps to ripen fruits faster. It develops attractive surface colour in the fruits. It is an easily available and cheap chemical. So, most farmers and fruit sellers use it to ripen fruits. Adverse effects of calcium carbide Local farmers used to ripen the fruit by storing them in dark and warm containers for many days. But nowadays calcium carbide is used to ripen fruit. It has potential health hazards. When we eat fruits ripened with calcium carbide, we can suffer from the following health hazards. i. A person will experience weakness, vomiting and thirst. ii. It can cause diarrhoea, burning sensation in chest and eye irritation. iii. It can also cause ulcers, sore throat and shortness of breath. iv. It causes heart complications and neurological disorders. v. Fruits ripened through calcium carbide are sweet on surface but sour in core. It's not as tasty as naturally ripened fruit. FACTS WITH REASONS Farmers should not use calcium carbide to artificially ripen fruits. Farmers should not use calcium carbide to artificially ripen fruits because of its potential health hazards such as heart diseases, neurological disorders and diarrhoea. Fig: fruits that are ripened from calcium carbide MEMORY TIPS Ethylene and Ethephon are also used in a limited concentration instead of calcium carbide as they are less harmful if compared with calcium carbide. Calcium carbide is already banned in Nepal.

440 cHemicalS uSed in daily life Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur ACTIVITY 4 If you have some unripe bananas, keep themon the top back side of the fridge for 2 days where it is warm. Observe the changes. Antioxidant The food can be spoilt and discoloured due to oxidation. Exposure to sunlight and oxygen starts oxidation. Usually, fatrich foods are mostly ruined by oxidation. Such foods can be preserved for many months if oxidation can be prevented. Some common ways to prevent oxidation are smoking, salting, fermenting or adding antioxidant. Natural chemical substances such as ascorbic acid and tocopherols can be used to prevent the oxidation of food. Synthetic chemical substances such as butylated hydroxytoluene and tertiary butylhydroquinone can also be used as an antioxidant. The chemical substances that are mixed in the food to prevent oxidations are called antioxidants. Some common antioxidants used to prevent oxidation of food are vitamin C, vitamin E, selenium and beta-carotene. Antioxidants help to preserve the taste and colour of the food so that food remains edible for a very long time. Adverse effects of antioxidants i. An excessive quantity of beta-carotene can cause lung cancer in smokers. ii. High doses of vitamin E can cause prostate cancer. iii. Some antioxidants will be harmful as they can interact with some medicines we consume. iv. It can accelerate the ageing process in our body. FACTS WITH REASONS We should not consume food that contains high doses of antioxidants. We should not consume food that contains high doses of antioxidants because it can increase the chance of cancer in our bodies and make us age faster. ACTIVITY 5 What natural substances can be used as an antioxidant to preserve food? Find out. Chemical Pesticides Agriculture is the source of food for all humans. However, agriculture is delicate. It is prone to diseases, drought, pollution, soil erosion, insects, rodents, fungi, bacteria and other Fig: vitamin C Fig: vitamin E MEMORY TIPS Colourful fruits and vegetables are the most potent source of antioxidants. Every colour contains a different antioxidant.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 441 animals.Crops like wheat, millet, gram, ground nut, and sugarcane are usually damaged by rats. To protects these crops from pests, fungus and rodents, Nepalese farmers are heavily dependent upon chemical insecticides, pesticides, fungicides and rodenticides. Pesticides are those chemical substances which are used to kill or chase insects, rodents, termites, fungi, etc. Benzene hexachloride, dichloro diphenyl trichloroethane are some organic insecticides and lead arsenate and calcium arsenate are some inorganic insecticides that are used to kill insects. Locally available chemicals such as wood ash, sulfur, neem plant, a tobacco plant, dhungriflower, gandhejhar, banmara plant, etc. can be used to control the pest. However, most farmers are attracted to chemical pesticides because these chemicals are easily available and have quick action on pests, rodents and fungi. Chemical insecticides have immediate and long-term adverse effects on our health. It can cause eye irritation, rashes, blisters, diarrhoea, nausea, blindness, cancer and even death. It is also harmful to the soil, water and ecosystem. These agrichemicals are deadly poisonous. Farmers must learn safety measures for storing, transporting and using these chemicals. Fig: pesticides Types of pesticides 1. On the basis of degradation and non-degradation Pesticides can be classified into two groups based on how biodegradable they are as biodegradable and non-biodegradable. a. Biodegradable pesticides Biodegradable pesticides are those pesticides that are broken down into harmless compounds by microbes, bacteria and fungi. They are less toxic to mammals including humans. They decompose faster in nature due to air, water, sunlight and microbes. So they are also called non-persistent pesticides. They leave a low residue. They are comparatively less harmful to the environment. Examples, malathion, dimethoate, jhol-mol b. Non-biodegradable pesticides Non-biodegradable pesticides are those that are usually stable and do not decompose. They are highly toxic to humans. It can cause cancer. They are MEMORY TIPS Pesticides were first introduced in Nepal in 1952. DDT was used to kill the mosquitoes that spread malaria. Farmers use around 396 gram of pesticide per hectare in Nepal nowadays. 80% of insecticides mix into the environment.

442 cHemicalS uSed in daily life Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur mostly organochlorines. They are insoluble in water and remain in body fat. They are also called persistent pesticides because they resist decomposition and stay in the environment for a longer duration. They are banned in Nepal and most countries. Examples, Dichlorodiphenyltrichloroethane (DDT), Benzene Hexachloride (BHC) 2. On the basis of target organisms Pests are harmful creatures that harm our crops, furniture, pets and domestic animals. Pesticides can also be classified based on the pest they kill. a. Insecticides The toxic chemical substances that are usually used to kill or chase or disturb the reproduction of insects are called insecticides. Examples, fenvalerate, malathion, cypermethrin, nitenpyram, etc. b. Herbicides Herbicides are poisonous chemicals that are usually used to kill undesired plants. Examples, metribuzin, isoproturon, atrazine, butachlor, etc. c. Rodenticides Rodents are usually mammals with very sharp canine teeth that grow continuously. Rabbits, rats, squirrels etc. are some common rodents. The toxic substances which are used to get rid of rodents are called rodenticides. Examples, warfarin, zinc phosphide, bromadiolone, coumatetralyl, etc. d. Bactericides Bacteria can also damage our crops. The poisonous chemicals used for killing or preventing the reproduction of bacteria are called bactericides. Examples, streptomycin sulphate, oxytetracycline e. Fungicides Mucor, yeast, mushrooms, etc. are some common organisms of the fungi kingdom. Some of them are parasitic on our crops. They decompose tonnes of food and kill plants. Some of them cause disease in humans and domestic animals. Those chemical compounds that are used for killing fungi are called fungicides. Examples, captan, dithiocarbamates, dimethomorph, sectin, mancozeb, etc. f. Larvicides The poisonous chemical substances that are usually made to kill larva of insects are called larvicides. They are usually sprayed in ponds to kill the larva of mosquitoes. Examples, oil, Methoprene, etc. g. Miticides Mites, ticks, lice and fleas are some parasites that harm our pet animals and domestic animals. Some of them harm us too. The chemicals used to get rid of mites and ticks are called miticides. Examples, azobenzene, fenazaquin, propargite, fenpyroximate 3. Based on route of entry or mode of action a. Contact pesticides The chemical compounds that can kill insects, herbs, larvae, etc. that come in direct contact are called contact pesticides. For example, Herbicides can kill

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 443 weeds when it is sprayed on the herbs. Examples, DDT, malathion, etc. b. Systemic pesticides Systemic pesticides are toxic chemicals that are absorbed by the body of an organism and distributed all over the body by the transportation system. It can kill the parasites within the body of organisms. Examples, potassium cyanide, multineem, bio-multineem, carbamates, neonicotinoid, etc. c. Stomach pesticides The toxic chemicals that must enter the body through the mouth into the digestive system are called stomach pesticides. They can kill the animals when consumed. It can cause headaches, nausea, diarrhoea, etc. Examples, lead arsenate, malathion, fenvalerate, cypermethrin d. Fumigant pesticides The fumigants are those toxic chemicals that change into gas when exposed to moist air and kill the animals if inhaled. It could be solid, liquid or gas. Examples, methyl bromide, nicotine, naphthalene, aluminium phosphide, etc. 4. Based on the origin Based on origin, insecticides are classified as organic (derived from hydrocarbon, for example, DDT), inorganic (derived from mineral for example lead arsenate) and biopesticides (derived from plant and animal for example jhol-mol). Precautions while storing pesticides i. Follow the instructions of manufacturer’s for storage. Never remove the label. ii. Store agrichemicals in original container. Do not pour into other containers. iii. Keep agrichemicals far away from source of fire. iv. Keep it far away from reach of children and animals. v. It should be stored in a locked and well-ventilated room without sunlight. vi. We should never store nearby food. Precaution while transporting pesticides i. Agrichemicals should be transported separately from food products. ii. There should be no passengers in a cabin which contains agrichemicals. iii. We should use proper safety gear while transporting it. iv. We should avoid, leakage and splashing while transporting it. FACTS WITH REASONS Agrichemicals should be handled with caution. Why? We should not consume food that contains high doses of antioxidants because it can increase the chance of cancer in our bodies and make us age faster. MEMORY TIPS Around one-third of the world’s potential crop production is lost annually because of weeds, pests and diseases, according to a report written jointly by Food and Agriculture Organization.

444 cHemicalS uSed in daily life Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur ACTIVITY 6 If there is a container of pesticide, read the label and directions to store, transport and use it. Wear gloves and a mask before holding it. Precaution while using pesticides i. Farmers should be trained for using chemical insecticides, fungicides and rodenticides. ii. One should use gloves, apron, boots and gas masks while using agrichemicals. iii. One should never eat or drink while using agrichemicals. iv. Farmers should use only required quantity of chemicals. v. Farmers should use chemical kits to reduce splashes and spills while using agrichemicals. vi. Farmers should make sure that non-target animals, insects, birds and children are not exposed to it. Poisonous chemicals used in homes Pesticides means chemical substances that are used to kill, control or chase pests. Baygon can be used to kill insects such as grasshoppers, wasps, spiders, ants and mosquitos in our house. Insecticides or certain shampoos are used to get rid of lice and fleas. Fungicides such as Miconazole is used to treat fungal infection on skin and feet. Rodenticides are used to kill rats that destroy our clothes, carpets and wooden furniture. Acids are corrosive chemicals. They are usually used to clean toilet bowls, bathroom tiles, and basins in the kitchen and bathroom. Chlorine is a useful chemical to get rid of bacteria and moulds. It is usually mixed in water to kill germs. It is also added to sewage to kill germs. Fig: acid used to clean basin Fig: chlorine to purify water Fig: mosquito repellent FACTS WITH REASONS Chlorine is frequently added to the swimming pool. Chlorine is added frequently in the swimming pool because it reacts with water to form an acid that can kill germs, bacteria and protists. ACTIVITY 7 Four milligrams of chlorine per litre water is not harmful to us. Inform your guardians to use the correct amount of chlorine in drinking water tank. MEMORY TIPS Acid can be mixed with water and poured down into the toilet bowl to kill germs. It should be kept there for a few hours.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 445 Precautions during their storage and transportation Insecticides, pesticides, fungicides, rodenticides, bleaching powder, acids and chlorines are commonly used in the house to get rid of germs and moulds. Since they are corrosive and poisonous, they should be stored, transported and used very carefully. They can burn our skin and eyes. They can kill us either. Precaution while purchasing pesticide i. We should purchase only those pesticides that are allowed by constitution of Nepal government on Pesticide rules, 2050. ii. We should consult with agriculture officer and get approval before buying highly toxic pesticides. Safety measures while storing i. These chemicals should be stored in a locked and ventilated rooms. ii. They should be kept out of reach of children and teenagers because there people are more vulnerable than adults. iii. Each type of harmful chemical should be stored separately to avoid reactions. iv. They should be kept away from fire. v. Never store them nearby food, fruits and vegetables. Safety measures while transporting i. Avoid spilling while transporting poisonous chemicals. ii. Do not transport poisonous chemicals along with food and clothes. Chemicals used in cleaning While doing different jobs our bodies as well as clothes become dirty. Similarly, the household materials like bed cover, sofa, chair, table, curtains, cooking utensils, cups, plates, spoons, etc. also become dirty time and again. They get different colours, dirt, dust, germs as well as smell. These foreign materials may also associate with different diseases. Thus, it is necessary to remove these foreign things using different kinds of substances called cleaning agents. The chemical substances which are used to remove dust, dirt, germs, foul smell, stains, etc. are called cleansing agents. There are two types of cleansing agents. They are: Traditional (natural) cleansing agents Our ancestors used different kinds of natural substances like Reetha, Amla, Shikakai, wooden ash, lemon juice, clay, etc. for cleaning purpose. They are called traditional cleansing agents. Reetha, Amla and Shikakai In ancient time, Reetha, Amla, Shikakai, etc. were used to clean hairs. This is because they are natural and free from harmful chemicals. They help in removing dandruff, strengthens hairs, preventing hair loss, etc. Use of these materials makes hairs more shiny and healthy in appearance. Wooden ash In the past, wooden ash was popularly used as a cleansing material. When wooden ash is mixed with a bit of water it forms a paste. This paste can be used as a mild abrasive to clean stained metals and dirty glasses. It also removes adhesives and sticky residue, stain,dirt, dirt, etc. from the clothes, cups, plates and cooking utensils. Like soap, ash is also a disinfecting alkaline agent. The World Health Organization recommends ash as an alternative when soap is not available.

446 cHemicalS uSed in daily life Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Hand cleaning with ash might remove the virus, bacteria, fungi and protozoa. However, chemicals in the ash could also damage the skin. Mustard Peena Mustard peena is obtained during the extraction of mustard oil. Peena has different types of vitamins like B6 , niacin, thiamin, etc. It is used for washing strengthening and softening the hair. Peena can also be used as a compost fertilizer. Sajeevan It is multipurpose plant that is grown in different parts of Nepal. It needs very little water to grow. So it can be grown in poor and infertile soil. Its anti-microbial, anti-cancer and antiHIV activity has been well recognized. It can be used to brush teeth. Its leaves can also be used to make compost fertilizer. Oil content in the seeds could be 30% to 48% but it can vary. It's oil is also widely used to make soap and glycerin. It is also called biodiesel because it can be used to power vehicles. It is also used for lighting. Lemon juice The lemon juice is one of the best all-natural cleaners. It is rich in citric acid and full of antibacterial properties. It removes adhesives and sticky residue, stain,dirt, dirt, etc. and makes utensils shiny. It is an effective, affordable and eco-friendly way to clean at the home. Importance of natural cleansing agents 1. They are available in natural substances. 2. They do not cause air, water and soil pollution. 3. They do not cause negative impact on the human health. 4. Most of the natural cleansing substances have pleasant smell. Modern(synthetic) cleansing agents We are familiar about soap, shampoo, detergents, sanitizer, stain remover, etc. They are manmade synthetic cleaners. These synthetic cleaners are used to remove dust, dirt, germs, foul smell, stains, etc. Soap and detergents are most popular synthetic cleansing agents. Soap is made from the animal fat or plant fat whereas detergents are made from the petroleum byproducts. So, soaps are biodegradable and detergents are non-biodegradable. Soap and detergents when dissolved in water possess the ability to remove dirt from the surfaces such as the human skin, textiles, and other solids. Soap Soap is a cleansing agent prepared by heating fat or oil with sodium hydroxide. It is used to clean our body, clothes, utensils and several other household objects. Chemically soap is a sodium salt of higher fatty acid that has cleansing property in water. For example, sodium sterarate (C17 H35 COONa), sodium palmitate (C15H31 COO Na), sodium oleate (C17 H33 COO Na), etc. Simple soap is prepared by heating vegetable oil of olive, coconut, cotton seeds with sodium hydroxide (NaOH). Similarly, quality soap is prepared by heating animal fat (mutton) with