Modern Concept Science and Technology 10

396 somE GasEs Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 397j. Write a chemical reaction to show the effect of acid rain on the marbles of archaeological castles. i. CaCO3+ dil. 2HCl CaCl2 + CO2 + H2O ii. 2NH4Cl + Ca(OH)2 CaCl2 + 2NH3 + 2H2Oiii. AgNO3 + NaCl AgCl + NaNO3 iv. CaCO3 (s) + H2 SO4 (aq) CaSO4 (s) + CO2 (g) + H2O (l) a. i b. iii c. iv d. ii e. iii f. i g. iii h. i i. iii j. iv Ans of MCQSTEP22. Very short questions a. What are A and B in the figure? b. Why do industrial areas experience frequent acid rain?c. Write the chemical formula of lime water d. Which salts contain carbon dioxide in combined form?e. What happens when we insert moist blue litmus paper inside a gas jar of carbon dioxide? f. Why is this gas not collected in the gas jar by the downward displacement of water?g. What is formed when a glass rod dipped in hydrochloric acid is introduced to the mouth of the gas jar that contains ammonia gas? h. The carbon dioxide can trap the heat of the sun and keep the earth warm. What is this process called?i. Write down the names of any two greenhouse gases.STEP33. Short questions a. Rushma is cleaning the marbles in the ladder of her house with the help of acid she bought from nearby hardware. A certain gas is produced from marble when she is cleaning the marbles with acid. Draw the diagram for laboratory preparation of that gas. b. Why is the solution in the second picture turning milky white? Explain.c. Draw the electron dot diagram of carbon dioxide gas.AB

398 somE GasEs Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 399d. Why is the gas jar kept inverted during the laboratory preparation of ammonia gas?e. What happens to the litmus paper shown in the diagram? f. How is urea prepared from ammonia? Describe in brief.g. In a practical exam, you have been given an eggshell, hydrochloric acid, conical flask, thistle funnel, cork, delivery tube, gas jar and litmus paper. To test this gas, teacher has suggested to methods. A : It passes through limewater to make a milky white precipitate.B : It passes through water to make liquor ammonia. One of these is a correct method and another one in incorrect. Which one is the correct testing method of this gas? h. Study the given news article and answer the following.[The average annual maximum temperature of the country Nepal has risen by 0.06 degrees Celsius, according to a recent study conducted by the Department of Hydrology and Meteorology (DOHM). The climate of the hilly region resembles that of Terai, with naked rocks being exposed at high mountain peaks, fruits and vegetables like mangoes and tomatoes growing in the hilly region too, rhododendrons blossoming earlier than usual, etc. are some latest changes seen in Nepal. “We see heavy rainfall in a short period. Extreme rainfall has the potential to cause water-induced disasters like floods and landslides,” said Baidya.Source: The Kathmandu post Posted: 28 Aug 2017 ]What phenomenon is the cause of this problem? Which gases are mainly responsible for this problem? Give two examples. What can we do to mitigate this problem in Nepal? STEP44. Long questions a. A substance X is used as a building material and is not soluble in water. When reacting with dilute HCl, it produces a gas which turns lime water milky. Based on this information, write the answer to the following questions.(i) What is this substance? (ii) Write a balanced chemical equation of the reaction involved. (iii) To what colour does the gas change a wet litmus paper?

398 somE GasEs Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 399b. Draw a clean diagram of the laboratory preparation of ammonia gas and label the lime tower. Also, write the balanced chemical equation of the reaction involved in this process.c. Study the given diagram and answer the following questions.Mixture of Ca(OH)2and NH4ClAmmonia gasLime towerCaOBurner StandStandi. Which coloured litmus paper is used to identify this gas?ii. Why does this gas is collected in an inverted gas jar?iii. What happens when a lime tower is not used to collect this gas?d. Observe the given activity and answer the following questions. The water trough contains phenolphthalein mixed water and the round bottom flask contains ammonia gas. When the apparatus is adjusted as shown in the diagram. The fountain can be observed. In the above experiment, there is ammonia inside the round bottom flask and the water from the trough is rising. Which two properties of ammonia are observed in this activity? Enlist. Write the balanced chemical reaction that occurs inside the round bottom flask in this experiment. e. Farmers make plastic tunnels to grow vegetables. What are these structures called? How do these structures trap heat? How will it benefit farmers?♦♦♦NH3Round bottom flaskWaterStand

400 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 401Key terms and terminologies of the unit1. Metals : The metals are hard, shiny, good conductor and electropositive elements.2. Non-metals : The non-metals are elements that are insulators, electronegative and dull. 3. Minerals : Minerals are compounds that are found in the earth's crusts. It could be metallic, non-metallic or fuel mineral.4. Rocks : Rocks are hard substances made of many minerals. 5. Ore : Ore is a rock which contains more amount of metals and is used for extracting metals profitably.6. Metallurgy : The process of extracting metals from its ores using various steps is called metallurgy.7. Mining : The process of digging ores from the crust is called mining.8. Crushing : The process of breaking ores into powder is called crushing. 9. Concentration : The process of removing gangue from ore is called concentration. 10. Oxidation : The process of heating ores strongly with or without air to change ore into metal oxide is called oxidation.11. Roasting : The process of heating ores strongly in the presence of air to change ore into metal oxide is called roasting.12. Calcination : The process of heating ores strongly in the absence of air to change ore into metal oxide is called roasting.13. Reduction : The process of making metal free from metal oxide is called reduction.14. Smelting : The process in which metal oxide is heated at a temperature higher than the melting point of metal in the presence of a reducing agent such as carbon to obtain free metal is called smelting. 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)UNITMetals17Estimated teaching period Theory Practical4 1Bishal Nath Upreti, born on April 22, 1951, in Kathmandu, is a distinguished geologist at Tribhuvan University's Department of Geology, specializing in Nepalese geology. Through his extensive teaching and research, he has made significant strides in understanding geological processes and hazards in the region. Upreti's expertise in engineering geology has played a vital role in facilitating infrastructure development and disaster management efforts in Nepal, highlighting his invaluable contributions to the field.’Bishal Nath UpretiAbout the Nepalese Scientist

400 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 40115. Refining : The process of removing slag from free metal is called refining.16. Distillation : The process of separating slag from free metal by strongly heating metal, if they have different boiling points is called distillation. 17. Electrorefining : The process of separating pure metal from slag by using electrolysis methods is called electrorefining. 18. Gangue : The unwanted materials present in powdered ore is called gangue. 19. Slag : The unwanted materials present in molten ore during reduction is called slag. IntroductionMetals 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 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. Mineral can be classified as metallic, non-metallic and fuel mineral. Mostly silicate minerals (90%) are found in the earth's crust. The minerals of sulphides, oxides, carbonates, sulphates and phosphate are also found in the earth’s crust. Minerals such as haematite, granite, cuprite, limestone, talc, red clay, coal, conglomerate, dolomite etc. are found in different parts of Nepal such as Nawalparasi, Palpa, Lalitpur, Gulmi, Dang, Salyan, Rolpa, Pyuthan etc. They are used for construction, decoration and ornaments.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. MEMORY TIPSAll minerals are not ores but all ores are minerals.

402 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 403Differences between Minerals and Ores.SN. Minerals SN. Ores1. 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. MetallurgyMetallurgy is the process by which we can get pure metals from their ores. Metallurgy involves several steps. The main steps are given below: i. MiningThe process in which ores are dug from the ground is called mining.ii. Crushing of oreThis step is used to convert big pieces of ores into smaller ones. iii. Powdering of oreIn this step, pieces of ores are converted into powder form. iv. Concentration of oreIn 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.a. Gravity separation / hydraulic separationSome ores have a higher density than the impurities in them. So, impurities can be washed away by a flowing stream of water. The denser ores will remain at the bottom. Fig: gravity separation

402 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 403b. Forth floatationSome ores are hydrophobic (move away from water) or hydrophilic (move toward water). So, hydrophobic or hydrophilic ores can be separated from the gangue by putting powdered ore in the mixture of water and pine oil and then agitating it with a jet of air. The ores will be collected in the froth that floats at the top of the water. c. Magnetic separationSome ores such as haematite are magnetic. So, magnets can be used to separate them from gangue. v. Oxidation of MetalThe act of converting ores into simple metal oxide is called oxidation. Oxidation is carried out by heating the ore in the presence or absence of air. Calcination and roasting are two methods of oxidation.a. CalcinationIt is a process of oxidation preferred for those compounds which have oxygen atoms in them already. The heated ores such as carbonates will turn into metal oxides. Water and other volatile impurities will be evaporated. It is mostly preferred for carbonate ores. Ores are heated in the presence of less amount of air during calcination.b. RoastingIt is a process of oxidation preferred for those ores which usually do not have oxides. The heated ores will absorb oxygen and change into metal oxides. It is mostly preferred for sulphide ores. Ores such as zinc sulphide are heated in the presence of more amount of air during roasting.vi. Reduction of metal oxidesOxidation gives us metal oxides. These metal oxides can be converted into free metal. The process of obtaining the free metal from the metal oxide is called reduction. Heating, smelting and electrolysis are some methods of reduction. Highly stable metal oxides such as aluminium oxide, magnesium oxide, calcium oxide, potassium oxide, sodium oxide etc, are reduced by electrolysis methods because they won’t reduce on heating. They are more reactive than reducing agent (carbon). If the metal oxides are stable such as zinc oxide smelting is preferred. Smelting is the act of heating metal oxides in the presence of strong reducing agents such as carbon, hydrogen, carbon monoxide etc. Fig: froth floatation

404 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 405Unstable metal oxides such as silver oxide can be reduced into free metal by simply heating. vii. Refining of metalHere, 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. Metals such as mercury is refined by distillation.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 1Let's practice electrorefining in the science laboratory. Take a beaker, DC source, impure copper rod (anode) and pure copper rod cathode. Put water in the beaker, dissolve copper sulphate, put anode and cathode and then turn on the switch. Video record the reaction for a few hours. Then observe in fast-forward mode. See the changes. 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:IronSymbol FeAtomic number 26Atomic weight 56Valency 2 or 3Electronic configuration 1s2, 2s2 2p6, 3s2 3p6, 4s2,3d6Position in periodic table Period = 4, Group = 8, Block = d – BlockOccurrenceIron is very reactive so it is always found in combined form. So, all ores of iron are compounds. Fig: Copper refining

404 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 405Ores of Iron1. Haematite Fe2O3 (chief ore) 75% iron2. Magnetite Fe3O43. Siderite FeCO34. Limonite 2Fe₂O3 . 3H₂O5. Iron pyrite FeS2Among 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 Ironi. Iron is a shiny and gray white, i.e., ash colored metal.ii. Its specific gravity is 7.86. iii. Its melting point is 15000C and boiling point is 25000C.iv. It is a good conductor of heat and electricity.v. It is malleable and ductile.vi. It becomes non-magnetic when heated above 7700C.Uses of IronIron is heavily used in construction, plumbing pipes, parts of vehicles, utensils, weapons, statues, manufacture of steel etc. AluminiumSymbol AlAtomic number 13Atomic weight 27Electronic configuration 1s2, 2s2 2p6, 3s2 3p1Valency 3Position in periodic table Period – 3, Group - 13, Block = p – BlockOccurrenceAluminium is very reactive so it is always found in combined form. So, all ores of aluminium are compounds. Ores of Aluminium1. Bauxite Al2O3.2H2O (chief ore) 40 to 60 % aluminium2. Cryolite Na₃AlF₆3. Felspar K(AlSiO₃.O₈)4. Corundum Al2O3Physical properties of aluminiumAluminium is a solid bluish-white metal with a specific gravity of 2.7. It is a light rust-free metal. Haematite oreBauxite ore

406 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 407FACTS WITH REASONSThough 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 aluminiumi. 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.CopperSymbol CuAtomic number 29Atomic weight 63.57Valency 1 or 2Electronic configuration 1s2, 2s2 2p6, 3s2 3p6, 3d10, 4s1Position in periodic table Period – 4, Group - 11, Block – d – BlockOccurrenceLess 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 copper1. Copper pyrite (Chalcopyrite) CuFeS₂ (chief ore, 34.5% copper)2. Cuprite Cu₂O3. Chalcocite (copper glance) Cu₂S4. Malachite Cu(OH)₂. CuCO₃5. Azurite [Cu(OH)₂. 2CuCO₃]Physical properties of copperCopper is a solid reddish-brown metal with a specific gravity of 8.95. It is a malleable and ductile metal. It is a very good conductor of heat and electricity. Chalcopyrite ore

406 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 407Uses of copperi. 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. SilverSymbol AgAtomic number 47Atomic weight 107.88Valency 1Electronic configuration 1s2, 2s2 2p6, 3s2 3p6, 3d10 , 4s2, 4p6, 4d10, 5s1Position in periodic table Period – 5, Group - 11, Block = d – BlockOccurrenceSilver 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 Silver1. Argentite (silver glance) Ag₂S (Chief ore, 87% silver)2. Horn silver AgCl3. Silver copper glance (AgCu)₂S4. Ruby silver (Pyrolite) 3Ag₂S.Sb₂S₃Physical properties of silverSilver is a shiny white metal with a specific heat capacity of 10.5. It is a malleable and ductile metal. It is a very good conductor of heat and electricity. Uses of silveri. 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.GoldSymbol AuAtomic number 79Atomic weight 197.2Argentite ore

408 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 409Valency 1 or 3Electronic configuration 1s2, 2s2 2p6, 3s2 3p6, 3d10,4s2 4p6 4d10, 4f14, 5s2 5p6 5d10, 6s1Position in periodic table Period – 6, Group - 11, Block – d – BlockOccurrenceGold 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 goldGold is present in alluvial sand or alluvial soil or quartz veins and calaverite (AuTe2).Physical properties of goldGold is a shiny yellow metal with a specific gravity of 19.3. It is the most malleable and ductile metal. It is a very good conductor of heat and electricity. FACTS WITH REASONSGold is concentrated and collected by gravity separation or hydraulic separation. Gold is concentrated and collected by gravity separation or hydraulic separation because gold is a denser metal than its impurities. So, when the stream of water flows through the alluvial soil, the soil is carried away by water and the denser gold remains in the vessel.Uses of goldi. 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 WorkUsing plastics, make an artificial greenhouse and display in the class.Calaverite oreMEMORY TIPSGold is the least reactive under normal conditions. So it is called noble metal.

408 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 409HOT SKILL HIGHER ORDER THINKING SKILL1. How is metallurgy a stepwise process? Explain. To obtain pure metal from ores, various methods should be carried out step-wise. So, metallurgy is called a step-wise process. Some common metallurgical steps are mining, crushing, concentration, oxidation, reduction and refining.Mining: It is the act of digging ores from its mines.Grinding and pulverization: The large ores are crushed and pulverised into fine powders. Concentration: Gangue are unwanted impurities present in ores. These gangue can be removed from powdered ore by gravity separation where ores are washed by water current, froth floatation where ore is mixed in oil and water and then agitated by air and magnetic separation where magnetic ores are pulled by magnet. Oxidation: After concentration ores are heated strongly with the presence of air (roasting) or without the presence of air (calcination) so that they will change into metal oxide. Reduction: Reduction is a method used to change metal oxides into free metals. Electrolysis, heating and smelting are three methods of reduction. Carbon, hydrogen, carbon monoxide etc. are some reducing agents used during smelting. Refining: The free metals obtained from reduction can still have some impurities called slag. It can be removed either by heating very strongly (distillation) or by using electrolysis (electro-refining). Therefore, metallurgy is a step-wise process. 2. Argentite is concentrated by froth floatation.Argentite is concentrated by froth floatation because it is hydrophobic, it moves away from the water. Argentite is a sulphide ore of silver. So, when it is mixed with water and pine oil and agitated by the jet of air, the sulphide ore sticks to the oil and comes up in the froth. 3. Oxidation and reduction The differences between oxidation and reduction are:SN Oxidation SN Reduction1 Oxidation is performed on concentrated ores.1 Reduction is performed on oxidised ores.2 Oxidation is a metallurgical step in which ores are changed into metal oxide by heating.2 Reduction is a metallurgical step in which oxidised ore is changed into free metal. 3 Roasting and calcination are a few methods of oxidation.3 Electrolysis, heating and smelting are a few methods of reduction. 4. Why is reduction carried out at a higher temperature than the melting point of metal? Reduction is carried out at a higher temperature than the melting point of metal because at that temperature the metal will melt and leave the slag. 5. We must use the salt of the metal that needs to be refined during electrorefining.We must use the salt of the metal that needs to be refined during electrorefining because if the salt of

410 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 411another metal is used, then the other metal will be collected on the cathode. We cannot obtain pure metal. 6. During the electrorefining of copper, Sora connected free copper obtained from reduction into the cathode and pure copper at the anode. Then she put ferrous sulphate salt into the water and passed DC. What are the mistakes she made? List out. What are the disadvantages of this mistake? How can she correct this mistake? Explain.As mentioned in the question her mistakes are: i. She connected free copper obtained from reduction into the cathode. Free copper obtained from reduction should be kept on the anode during electrorefining.ii. She connected pure copper to the anode. Pure copper should be connected to the cathode during electrorefining.iii. She used ferrous sulphate but she must use salt of copper. The disadvantages of these mistakes are:i. Free metal obtained from reduction will not change into pure metal.ii. Pure metal will also deposit over impure metal.iii. Some iron molecules of ferrous sulphate will be deposited over the cathode.iv. The metal will be more impure than earlier. She can correct this mistake in the following ways:i. connecting pure copper on the cathode and free metal obtained from reduction to cathode.i. using salts of copper such as copper sulphate 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 change metal carbonates into metal oxides, remove moisture and remove other volatile impurities. Calcination is important because we can change carbonates into metal oxides. Metal oxides can be reduced to obtain metal. 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.

410 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 4114 STEPS EXERCISE EXERCISESTEP11. Multiple Choice Questions a. What minerals makeup 90% of the earth's crust? i. silicates ii. carbonates iii. soil iv. copper b. What is the objective of roasting the ore?i. to make it warm and melt it.ii. to remove impurities in the form of carbon dioxide iii. to convert ores to metal oxides iv. melt the metal so that it can flow out from container c. Which metal is extracted from siderite?i. Silver ii. Iron iii. gold iv. Aluminium d. Which one is argentite? Not oxidised by calcination Oxidised by calcination Concentrated by froth floatation A BConcentrated by gravity separation C D i. A ii. C iii. B iv. De. Which one is the correct order of steps of metallurgy?i. concentration grinding oxidation reduction refining ii. mining concentration reduction oxidation refining iii. mining concentration oxidation reduction refining iv. mining grinding refining oxidation concentration f. What is the objective of heating carbonate ores of metals?i. remove moisture, decompose carbonates into metal oxides, remove volatile impurities ii. converting ores to metal oxides, remove impurities, remove gangue iii. convert metal oxides to free metal, remove impurities by distillation, remove moistureiv. to decompose metal oxides into free metal, remove moisture, remove volatile impurities

412 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 413g. Which method A or B should we choose to change calcium carbonate into calcium oxide during metallurgical steps? Write the name of the process.A Oxidation B Presence of oxygen Absence of oxygeni. We should choose A. It is called roasting.ii. We should choose B. It is called roasting. iii. We should choose A. It is called calcination.iv. We should choose B. It is called calcination. h. Study the statement and arguments. Select the best comment. Statement: Magnet can separate iron dust from the mixture of iron dust, aluminium and sand.Argument 1: This process can be used for the concentration of iron during the extraction of iron.Argument 2: No! magnetic separation cannot be used here, because the magnet will attract aluminium too.i. Statement and argument 1 are correct. Argument 2 is incorrect. ii. Statement and argument 2 are correct. Argument 1 is correct. iii. Argument 1 and argument 2 are correct. The statement is incorrect. iv. Argument 1 and argument 2 are incorrect. The statement is correct. i. Which of the following are the processes of reduction? i. smelting, heating, electrolysis ii. froth flotation, smelting, heating iii. gravity separation, calcination, roasting iv. smelting, distillation, electro-refiningj. Write the molecular formula of iron pyrite.i. FeS2 ii. CuFeS2iii. Ag2S iv. FeCO3a. i b. iii c. ii d. i e. iii f. i g. iv h. i i. i j. iAns of MCQSTEP22. Very short questions a. What is kept in the anode during electrorefining?b. Oxidation and reduction process is not necessary to extract gold.c. What is the mistake in this experiment? Process Electrolyte used At anode At cathode Electrorefining of copper AgSO4 solution Copper obtained from smelting Pure copper d. Which step of metallurgy is shown in the diagram?e. Which metal is extracted from haematite ore?f. What mineral is the chief ore of aluminium? g. What are ores? Give any two examples.

412 mEtals Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 413h. Why is argentite concentrated by froth floatation?i. Which metal is mostly found in elemental form? STEP33. Short questions a. What is the advantage of oxidation reactions during metallurgy? b. Why is impure copper used as an anode and pure copper used as a cathode during the electrorefining of copper?c. Write the molecular formula of the following ores. i. Bauxite ii. Cryolite iii. Felspard. Differentiate between oxidation and reduction.e. Zinc sulphide is roasted instead of calcination. Why?f. All ores are minerals but all minerals are not ores. Give reason. g. Write the molecular formula of the following ores. i. Cuprite ii. Feldspariii. Copper glance iv. Malachite h. What types of ores are usually oxidized by roasting? Give an example. STEP44. Long questions a. What do you mean by the concentration of ore? Which type of method of concentration is useful for the following types of ores?i. very heavy ores such as gold ii. hydrophilic ores such as argentite iii. magnetic ores such as nickel b. How is reduction carried out? How are unstable, stable and highly stable metal oxides reduced? Explain with suitable examples. c. Describe the electrorefining of copper with a suitable diagram. d. What is oxidation? What types of oxidation are preferred for what types of ores? Explain with an example. e. What is the purpose of refining? Describes various methods of refining with an example. ♦♦♦

414 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 415Key terms and terminologies of the unit1. Hydrocarbons : The compounds that are made of hydrogens and carbons are called hydrocarbons. 2. Organic compounds : The hydrocarbons that are made of covalently bonded carbons and hydrogens and few foreign elements are called organic compounds or carbonic compounds. 3. Inorganic compounds : The compounds that are not made of covalently bonded carbons and hydrogens are called inorganic compounds or non-carbonic compounds. 4. Saturated hydrocarbons : The hydrocarbons in which there is a single covalent bond between two carbon atoms are called saturated hydrocarbons. 5. Unsaturated hydrocarbons: The hydrocarbons in which there are double or triple covalent bonds between two carbon atoms are called unsaturated hydrocarbons. 6. Alkanes : The hydrocarbons in which there is a single covalent bond between two carbon atoms are called alkanes. 7. Alkenes : The unsaturated hydrocarbons in which there are double covalent bonds between two carbon atoms 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.UNITHydrocarbon and Its Compounds18Estimated teaching periods Theory Practical5 1Ram I. Mahato, born in 1963 in Janakpur, is a distinguished professor at the University of Nebraska Medical Centre, renowned for his contributions to pharmaceutical sciences and drug delivery research. His pioneering work, particularly in non-viral vectors for gene therapy, has revolutionized therapeutic approaches, significantly enhancing drug delivery mechanisms and facilitating the development of innovative treatments. Mahato's ground-breaking research has had a profound impact on the field, shaping the future of pharmaceuticals and improving patient care worldwide. Ram I. MahatoAbout the Nepalese Scientist

414 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 4158. Alkynes : The unsaturated hydrocarbons in which there are triple covalent bonds between two carbon atoms are called alkynes. 9. IUPAC : IUPAC stands for International Union of Pure and Applied Chemistry. 10. Alkyl radical : The alkanes which have a positive charge after losing a hydrogen atom are called alkyl radicals. 11. Functional group : An atom or group of atoms that bonds with alkyl radicals and determines their properties are called functional groups. 12. Homologous series : The hydrocarbons which have similar properties and can be defined by the same general formula are called homologous series. 14. Alcohol : The hydrocarbon which contains an alcohol functional group is called alcohol (ROH). 15. Monohydric alcohol : The alcohol which contains only one hydroxyl functional group (-OH) is called monohydric alcohol. 16. Dihydric alcohol : The alcohol which has two hydroxyl functional groups (–OH) is called dihydric alcohol. 17. Trihydric alcohol : The alcohol which has three hydroxyl functional groups is called trihydric alcohol. 18. Glycerol : Glycerol is a colourless, sweet and viscous trihydric alcohol. 19. Glycol : Glycol is a colourless, viscous and antimicrobial dihydric alcohol.20. Hydrogenation : The process of making ghee from vegetable oil (unsaturated fatty acid) into vegetable ghee (saturated fatty acid) by passing hydrogen gas through vegetable oil in the presence of nickel is called hydrogenation. IntroductionCarbon 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 CompoundsThere are 118 elements but millions of compounds. These vast numbers of compounds are broadly divided into carbonic and non-carbonic compounds. The non-carbonic compounds are mostly made of elements other than carbon. However, some non-carbonic compounds such as oxides of carbon, metal carbonates, metal bicarbonates, carbides and carbonic acid still have carbon in them but they are not organic. Non-carbonic compounds are also called inorganic compounds. The branch of science in which we study physical and chemical properties and the uses of inorganic compounds is called inorganic chemistry. Carbonic compounds are those compounds which are usually made of carbon, hydrogen and few foreign elements. They have covalent bonds between them. The covalent bond MEMORY TIPSCarbon dioxide has carbon in it but its not an organic compound (hydrocarbon) because it does not have covalent bond between hydrogen and carbon.

416 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 417is formed when elements share electrons. In a hydrocarbon, the hydrogen atoms share electrons with carbon atoms to form short and strong covalent bonds. The covalent bond is also formed between two carbon atoms. These covalent bonds are slightly longer and weaker than the covalent bond between carbon and hydrogen. Since they have covalent bonds, they do not ionize in water. They have low melting points and boiling points. Most of them are combustible. They are usually insoluble in water except glycerol. They are mostly obtained from the body of living organisms. So, they are also called organic compounds. The branch of science in which we study about properties and uses of organic compounds is called organic chemistry. Organic compounds are very useful for us. Industrial chemistry is the branch of chemistry in which various carbonic compounds and non-carbonic compounds are researched, changed into products and made available for general uses. Multiple carbon compounds from multiple sources are collected, processed and used in society. Petroleum is the major source of (organic compounds) hydrocarbons. Biomass such as plant and animal parts is also the source of hydrocarbons. Carbohydrates, fats, enzymes and fats present in the animal body or human body are also sources of organic compounds.Some uses of organic compounds are: i. Alkane homologous series such as methane is used to make chloroform, ethane is used for welding and propane and butane is used as fuel.ii. Alcohol homologous series such as methyl alcohol is used as fuel, ethyl alcohol is used to sterilize surgical equipment, glycol is used as a cooling agent and glycerol is used to make soaps and cosmetics. iii. Petroleum are used as fuel. iv. Most medicines, foods, clothes etc. are organic compounds. HydrocarbonsCompounds which are formed by the combination of carbon and hydrogen are called hydrocarbons. For example, methane (CH4), ethane (C2H6), propane (C3H8), ethene (C2H4), ethyne (C2H2), 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 hydrocarbonsProject WorkUsing different local materials like toothpick, potatoes, tomatoes, grapes, etc. make different types of hydrocarbons.Saturated HydrocarbonsThe 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 (C2H6), propane (C3H8), 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:

416 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 417S.N. No. of carbon atoms IUPAC name Moleular formula Structural formula1. 1 (Meth) Methane CH4HIH–C–HIH2. 2 (Eth) Ethane C2H6H HI IH – C – C – HI IH H3. 3 (Prop) Propane C3H8H H HI I IH–C–C–C–HI I IH H H4. 4 (But)ButaneC4H10H H H HI I I IH–C–C–C–C–HI I I IH H H H5. 5 (Pent) Pentane C5H12H H H H HI I I I IH–C–C–C–C–C–HI I I I IH H H H HSaturated hydrocarbons, i.e. alkanes are chemically less reactive. So, they are also called paraffins (para-less, affins-reactivity).Unsaturated HydrocarbonsThe hydrocarbons in which there are double or triple covalent bonds between two carbon atoms are called unsaturated hydrocarbons. For example, ethene (C2H4), propene (C3H6), ethyne (C2H2), propyne (C3H4), etc. Unsaturated hydrocarbons are of two types.a) Alkenes b) Alkynesa) AlkenesThe unsaturated hydrocarbons in which there are double covalent bonds between two carbon atoms 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 given below:MEMORY TIPSThe process of making ghee from vegetable oil (unsaturated fatty acid) into vegetable ghee (saturated fatty acid) by passing hydrogen gas through vegetable oil in the presence of nickel is called hydrogenation.

418 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 419S.N. No. of carbon atomsMolecular formulaStructural formula IUPAC name1. 2 (Eth) C2H4 C = CH HH HEthene2. 3 (Prop) C3H6H–C–C = CHH HII IHHPropene3. 4 (But) C4H8 H–C–C–C=CHHHIHIHIHIHIButeneAlkenes are also called olefins because they react with chlorine and produce oil-like substances.b) AlkynesThe unsaturated hydrocarbons in which there are triple covalent bonds between two carbon atoms 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 atomsMolecular formula Structure IUPAC name1. 2 (Eth) C2H2 H–C ≡ C–H Ethyne2. 3 (Prop) C3H4 H – C–C ≡ C – HHIIHPropyne3. 4 (But) C4H6 H – C–C–C ≡ C – HHIHIIHIHButyne4. 5 (Pent) C5H8 H – C– C– C– C ≡ C – HHIHIIHIHHIIHPentyne

418 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 419IUPAC SystemThe 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 word root: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 suffix '-ane' after the word root.iii. An unsaturated hydrocarbon containing a double covalent bond is indicated by writing suffix '-ene' after the word root.iv. An unsaturated hydrocarbon containing a triple covalent bond is indicated by writing suffix '-yne' after the word root.For example: (i) H – C – C – C – HHIHIIHIHHIIHNo. of carbon atoms = 3∴ word root = PropType of bond = single covalent = ane∴ The name of the given hydrocarbon = Prop + ane = Propane(i) H – C = C – C – C – HIHIHHIHIIHIH No. of carbon atoms = 4∴ Word root = ButType of bond = Double covalent = ene∴ The name of the given hydrocarbon = But + ene = ButeneFunctional GroupA 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:

420 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 421S.N. Name of functional group Symbol Structure Organic compounds1. Hydroxyl –OH – OH Alcohol2. Carboxylic acid –COOH OII – C – OH Acid3. Ether –O– –O– Ether4. Aldehyde –CHOOII – C – H AldehydeAlkyl RadicalAlkanes are saturated hydrocarbons. Sometimes they lose hydrogen atoms and gain a positive charge. They are called alkyl radicals. The alkanes which have a positive charge after losing a hydrogen atom are called alkyl radicals. Its general formula is CnH2n+1. CH4- H CH3+Methane - H Methyl radical Homologous SeriesA 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 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 formulaMethane CH4 H – C – HHIIHCH4Ethane C2H6 H – C – C – HHIHIIHIHCH3CH3

420 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 421Propane C3H8 H – C – C – C – HHIHIHIIHIHIHCH3CH2CH3Butane C4H10 H – C – C – C – C – HHIHIHIHIIHIHIHIHCH3CH2CH2CH3Pentane C5H12 H – C – C – C – C – C – HHIHIHIHIHIIHIHIHIHIHCH3CH2CH2CH2CH3Some Important Organic Compounds and Their Usesa) 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.MethaneH – C – HHIIHMethaneUses of methanei. 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 (CH3OH), 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. Ethane (C2H6)Ethane is the second member of alkane series. It is a saturated hydrocarbon. It occurs in natural gas and petroleum mines.MEMORY TIPS Methane is also called marsh gas as it is found in marshy places.H – C – C – HHIHIIHIHEthane Ethane

422 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 423Uses of ethanei. 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 inflammable gas.H – C – C – C – HHIHIHIIHIHIHPropane PropaneUses of propanei. 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. H – C – C – C – C – HHIHIHIHIIHIHIHIHiso-butane n-ButaneUses of butanei. 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 IsomerismIsomers are organic compounds having the same molecular formula but different structure and properties. For example, n-Butane and iso-butane are two isomer of butane. AlcoholAlcohol 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. For example,MEMORY TIPSPropane (C3H8) is highly inflammable. So, it is used as a fuel in lighters.

422 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 423 HIHIIHIHH – C – H H – C – OH–H+OHMethyl alcohol or methanolTypes of AlcoholDepending on the number of hydroxyl groups, there are different types of alcohol. But in this unit, we study three types of alcohol:a. Monohydric alcoholAlcohol 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. For example HIHIHIHIHIHIIHIHIHIHIHIHH – C – HH – C – C – H H – C – C – OHH – C – OH–H+OH–H+OH(Methane) (Methyl alcohol or methanol)(Ethane) (Ethyl alcohol or ethanol)FACTS WITH REASONSEthanol is called monohydric alcohol.Ethanol is called monohydric alcohol because this alcohol contains only one -OH functional group. b. Dihydric alcoholAlcohol 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.For example,HIHIHIHIIH IOH IOHIHH – C – C – H H – C – C – H–2H+2OH(Ethane) (Ethylene glycol)H – C – C – C – C – OHHIHIHIHIIHIHIHIH(Butanol)

424 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 425c. Trihydric alcoholAlcohol 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.For example,HIHIHIHIHIHIIH I OH IOH IOHIHIHH – C – C – C – H H –C – C – C – H–3H+3OH(Propane) (Glycerol)Some Important Alcoholsa. 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+OHHIHIHIIHIHIHH – C – OH H – C – H H – C – OHUses of methyl alcoholi. It is used as fuel in spirit lamps.ii. It is for the preparation of formaldehyde and paints.iii. It is used for making synthetic clothes and dry-cleaning clothes.iv. It is used as an organic solvent. It can dissolve fat, oil and paint. v. It is used for making methyl chloride, perfume, dyes 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 as alcohol.(Ethanol)HIHIIHIHH – C – C – OH(Ethane) (Ethanol)HIHIHIHIIHIHIHIHH – C – C – H –H H – C – C – OH+OH

424 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 425Uses of Ethyl alcoholi. 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 is a dihydric alcohol. It has two hydroxyl functional groups in it. Ethylene glycol is a glycol with two carbons, each carbon contains an alcohol functional group. Its IUPAC name is ethan-1, 2-diol. It is also a colourless viscous liquid. It is an industrial chemical. It is used in industries. It is also used in the food industry. It is a preservative too. It is antimicrobial. It is also used as a cooling agent. Its formula is C2H4(OH)2 and condensed formula is CH2OHCH2OH.HIHIIOHIOH H–C–C–HStructural formula of ethylene glycolUses of glycoli. 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 not in the ether. (Propane) (Glycerol)HIHIHIHIHIHIIHIOHIOHIOHIHIHH–C–C–C–H H–C–C–C–H –3H+3OHMEMORY TIPSEthanol is used to make spirit, sanitizer etc.

426 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 427 HIHIHI IOH IOH IOHC3H5(OH)3 H – C – C – C – H CH2OH – CHOH – CH2OH(Molecular formula) (Condensed formula)(Structural formula)GlycerolUse of glyceroli. 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 SKILL1. Glycerol is used to heal cracks in the skin.Glycerol is used to heal cracks in the skin because it can retain moisture. It keeps skin moist and prevents loss of water and heat from the skin. As a result, the skin will be repaired. 2. Alkane is called paraffin. Alkane is called paraffin because it is a less reactive hydrocarbon. 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.4. Observe the given diagram. Write its structural formula and IUPAC name. CHHHO HThe given compound is methanol and the structural formula of a given compound is:HH C OHHMEMORY TIPS1. 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.

426 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 4275. Write the name of the given compound and identify whether it is saturated or unsaturated.H – C C – HThe given compound is ethyne. It is an unsaturated hydrocarbon because it has a triple bond. 6. What type of bond is found between hydrogen and carbon of the given compound? Why is the bond between its two carbon atoms weaker than the bond between carbon and hydrogen? C = CH HH HThe bond found between carbon and hydrogen in this compound is a covalent bond. The shorter covalent bonds are stronger than the longer covalent bonds. The covalent bond between the two carbon atoms of this compound is longer than the covalent bond between hydrogen and carbon atoms. Therefore the bond between its two carbon atoms is weaker than the bond between carbon and hydrogen atoms. 7. Glycerol is called trihydric alcohol. Glycerol is called trihydric alcohol because it contains three hydroxyl functional groups. One hydroxyl functional group 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 isH HH C C C HH HHydrogen 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. 4 STEPS EXERCISE EXERCISESTEP11. Multiple Choice Questions a. What is the general formula of alkyl radical?i. CnH2n+2 ii. CnH2n-1 iii. CnH2n-2 iv. CnH2n+1

428 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 429b. 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.c. Which one of the following is used as coolant?i. butane ii. glycol iii. ethanol iv. glycerol d. Which one of the following is the correct order of the alkene series?i. methene, ethene, propene ii. ethene, propene, butene iii. methane, ethane, propane iv. ethyne, propyne, butyne e. What are the features of glycerol?i. sweet, flammable, soluble in ether ii. flammable, sweet, gas iii. sweet, viscous, water-soluble iv. colourless, odourless, tasteless f. Ethane is used for welding metal.i. because it produces sufficient heat on combustion. ii. because it is antimicrobialiii. because it has a low melting point iv. because it is flammable g. Study the given statements and arguments. Statement: The compounds that are made of carbon and hydrogen are called organic compounds. It can contain some foreign elements too. Argument 1: Some carbon compounds such as carbon dioxide are not organic compounds even though they have carbon.Argument 2: Every compound made of carbon are organic compound. Which of the following comments is correct? i. Statement is true. Both arguments are wrong. ii. Statement is false. Both arguments are correct. iii. Statement and argument 1 are correct. Argument 2 is false. iv. Statement and argument 2 are correct. Argument 1 is false. h. What does Y represent in this table? General formula n = 2 Structural formula CnH2n + 1.OH C2H5OH XCnH2n YC = CH HH Hi. C2H2 ii. CH2CH2iii. CnH2n iv. C2H5OH

428 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 429i. Which of the following set is a functional group?i. C2H5OH, CH3OH, C2H4(OH)2 ii. CH4, C2H6, C3H8iii. C2H2, CCl4, CH3Cl iv. -O-, -OH, -COOHj. What happens if one hydrogen from each carbon is replaced by the -OH functional group in this compound?HIHIHIIHIHIHH–C–C–C–Hi. glycerol will be formed ii. glycol will be formed iii. vanaspati ghee will be formed iv. propanol will be formed a. iv b. iii c. i d. ii e. iii f. i g. iii h. ii i. iv j. i Ans of MCQSTEP22. Very short questions a. Write the structural formula of propane.b. Write the IUPAC name of the given compound. H HHCOHHCOHHCOHc. Which group among them does alcohol belong to?Hydrocarbon Derivatives of hydrocarbon Organic A BInorganic C Dd. Write the IUPAC name of the compound B. A Ethene B Sufficient hydrogen is supplied Sufficient hydroxyl functional group is supplied e. Which hydrocarbon is called marsh gas?f. Write the full form of IUPAC.g. Write the word root for a carbon compound which has 3 carbons.h. Name the compound having the following structural formula.i. What is the IUPAC name of methyl alcohol? C = CH HH H

430 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 431STEP33. Short questions a. Sugar turns black when heated. Give reason. b. Calculate the number of hydrogens in the 4th homologue of the alkyne series.c. When ethene is supplied with sufficient hydrogen atoms, an addition reaction starts to produce a certain hydrocarbon. Write a name and the use of that hydrocarbon.d. Write any two differences between alkanes and alkynes.e. Write the name of the given compound and identify whether it is saturated or unsaturated.f. Write any two uses of propane. g. Glycol is called dihydric alcohol. Why?h. What is a homologous series? Give an example.STEP44. Long questions a. Which alcohol is used to heal skin cracks and keep them moist and soft? Write its IUPAC name. How is it formed?b. Study the given structural formula and answer the following questions. i. Write the general formula of the given structural formula. ii. Write the name of the compound formed by the removal of one hydrogen by one 'OH' from the above compound.iii. Write any use of energy produced by the burning of the given compound.iv. Write the structural formula of the compound which is formed by placing a double bond between two carbons in the given structural formula.c. Define alcohol. How many types of alcohol are there based on the number of hydroxyl functional groups? Write the use of each type of alcohol. d. An example of a homologous series of alcohol is given above. Write down any two characteristics of this series. Why are the given compounds in one homologous series? CH3 – OH (Methanol) CH3 – CH2 – OH (Ethanol) CH3 – CH2 – CH2 – OH (Propanol) CH3 – CH2 – CH2 – CH2 – OH (Butanol )e. 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.♦♦♦HIHIHIIHIHIHH–C–C–C–HHHC HHC HH

430 hydRoCaRbon and its Compounds Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 431Key terms and terminologies of the unit1. Food preservation : The act of preventing spoilage of food by using various techniques or ingredients is called food preservation. 2. Food preservatives : Food preservatives are natural or synthetic substances that are mixed with food to prevent food spoilage. 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 amounts as they are prescribed. 5. Traditional food preservatives : The ingredients that are traditionally used to preserve food are called traditional food preservatives. 6. Chemical food preservatives : The industrially prepared chemical substances which are mixed in food to prevent microbial activities and prevent spoilage are called chemical food preservatives.7. Induced fruit ripening agents : Industrial chemicals such as calcium carbide that are used to artificially ripen fruits are called food preservatives for induced fruit ripening. 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. UNITChemicals Used in Daily Life19Estimated teaching periods Theory Practical5 1Dr. Shobha Poudel, born on January 26, 1953, in Bhojpur, Nepal, is a respected scholar whose career has been devoted to interdisciplinary research in global environmental studies, with a focus on climate change adaptation. Her contributions have been instrumental in advancing our understanding of climate change impacts and formulating effective adaptation strategies. Dr. Poudel's dedication to addressing environmental challenges has earned her prestigious awards, underscoring her commitment to making a meaningful impact in safeguarding our planet's future. Dr. Shobha PoudelAbout the Nepalese Scientist

432 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 4338. Calcium carbide : Calcium carbide (CaC2) is an industrial chemical that is used for ripening fruits artificially. 9. Antioxidant : The chemicals that prevent oxygen from coming in contact with foods and prevent spoilage are called antioxidants. 10. Pesticides : The chemical substances which are used to kill insects, herbs, rodents, termites, fungi, etc. are called pesticides. 11. Biodegradable pesticides : The pesticides that decompose into non-toxic materials when come in contact with water are called biodegradable pesticides. 12. Non-biodegradable pesticides : The pesticides that do not decompose into non-toxic materials when come in contact with water are called biodegradable pesticides. 13. Insecticides : Insecticides are poisons that are used to kill insects that harm crops, construction, clothes etc. is called insecticide. 14. Herbicides : The poisons that are used to kill unwanted herbs from our farms, gardens, moist walls etc. are called herbicides. 15. Rodenticides : The poisons that are used to kill rats, moles and other rodents are called rodenticides. 16. Fungicides : The poisons that are used for killing yeast, parasitic mushrooms and other fungi are called fungicides. 17. Miticides : The poisons that are used to kill mites are called miticides. 18. Contact pesticides : The poisons that kill pests that come in direct contact are called contact pesticides. 19. Systemic pesticides : The pesticides that are absorbed by plants and stored in tissues which kill anyone that eats that plant are called systemic pesticides. 20. Stomach pesticides : The pesticides that kill any pest that eats it are called stomach pesticides. 21. Fumigants : The pesticides that turn into vapour when come in contact and kill organisms that breathe them are called fumigants. 22. Cleansing agents : The substances that are used for cleaning the body, washing hair, washing clothes, cleaning marbles etc. are called cleansing agents. 23. Synthetic cleaners : Industrially produced chemicals used for cleaning are called synthetic cleaners. 24. Traditional cleaners : Reetha, wooden ash, sajiban, lemon juice, mustard peena etc. which are used for cleaning purposes are called traditional cleansing agents.25. Soap : The sodium salt of fatty acid that can remove dirt from clothes is called soap. 26. Detergents : Sodium salts of long-chain benzene sulphonic acid, that can wash clothes are called detergents. 27. Chemical pollution : The decrease in the quality or quantity of the environment due to the mixing of waste chemical products is called chemical pollution.IntroductionChemical substances are either organic or inorganic. Some of them are bio-degradable and some of them are non-biodegradable. These chemical substances can be used for various tasks. Industrial chemistry is a branch of science that deals with the use and effect of various chemical substances in society. Many chemical substances are produced industrially and used for human benefits. Many medicines are chemical substances. Natural ingredients or

432 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 433synthetic chemicals are used to preserve food. Many chemicals such as calcium carbide are used to artificially ripen fruits. Soap and detergent are artificial chemicals used for cleaning. Reetha, peena, lemon juice and sajiwan are natural ingredients used for cleaning. Chemical pesticides are used for chasing or killing pests. It might be natural substances or synthetic chemicals. Chemical fertilizers, cement, plastic, fibres, dyes and glasses are some industrial chemical substances used in our society. Heavy use of such chemical substances has decreased the quality of the surrounding ecosystem. We should be aware of chemical pollution and its effects and work together to reduce chemical pollution. Fig: detergent Fig: synthetic cleaners Fig: food additives Fig: food preservation Fig: chlorineFood preservativesFood preservation has always been challenging since ancient times. Foods are organic substances. They contain moisture. They are often infected with bacteria, viruses and fungi. The microbial activity is more in moist food. They spoil the food. Every civilization has tried multiple ways to preserve food. The act of preventing spoilage of food by using various techniques or ingredients is called food preservation. Some of the common practices are salting, sweetening, drying, smoking, using brine water, keeping it cold, boiling, canning, pickling, using spices, burying it in soil, covering it with wooden ash, jholmol, neem etc. Currently, modern technologies have made food preservation easier. Foods can now be pasteurization, boiled and canned, kept in a cold store, deep-frozen and refrigerated. Synthetic food preservatives are also available for food preservation. However synthetic food preservatives are harmful. Food preservatives are natural or synthetic substances that are mixed with food to prevent food spoilage. FACTS WITH REASONSPasteurization can prevent milk from spoiling.Pasteurization can prevent milk from spoiling because when it is boiled all the germs are dead. Since germs are dead, there will be no microbial activities. So, milk does not spoil. ACTIVITY 1Nowadays, people mostly use refrigerators to preserve food. How did people preserve food a few decades ago? Research. First class preservativesFirst class food preservatives are those which can be used in any amount without exact measuring. Example: Mustard Oil, Sugar, Turmeric, Salt, Smoke, spices, Vinegar, Honey, MEMORY TIPSHoney is antimicrobial. So, it can be used to preserve food.

434 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 435mug wort, Neem Oil, Chuk Amilo, Himalayan Salt, Red Chillies, Garlic, diatomaceous earth, brine water, pepper, etc. Second class preservativesSecond class food preservatives are those which must be used in exact amount as they are prescribed. Examples: Benzoic acid and its salts, Sulphuric acid and its salts, Sodium nitrate, Potassium nitrate, Sorbic acid, Calcium propionates, Sodium propionates, Propionates of lactic acid, Methyl or propyl Para hydroxy benzoates, Sodium diacetate, Sulphur dioxide, etc. Traditional food preservativesFood 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.Fig: pickled radish Fig: pickled mushroom Fig: pickled of cauliflowerFood preservation is a common practice in Nepal too. Multiple local technologies are being used for food preservation. Some common methods are drying, pickling, smoking, salting and sugaring. Mostly grains are dried in the sunlight. Vegetables such as radish, squash, cauliflower etc. are also cut into thin slices and dried. Some of these are also changed into pickles for preservation. They use chillies, turmeric, mustard oil, salt and other spices because these things reduce microbial activities. Some people change fruits into jams, add sugar or dip in honey so that fruits will last longer. Putting food in a strong salt solution or sugar solution also helps to reduce microbial activities and preserve food. Salt solution and sweet paste absorb water from the cells of microbes and kill them. Boiling food, storing it in cold and dry places, keeping it in a natural cold store or modern cold store, canning and pasteurization are also new modern methods being practised in Nepal regarding food preservation. Figure of oiled, smoked and then dried meatMEMORY TIPSSmoking is common in Nepal to preserve meat. They cut meat into thin slices and put it in smoke from firewood. Some of them even use salt, turmeric and mustard oil in them and they keep it in sunlight too. The meat will then last for a few months.

434 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 435FACTS WITH REASONSBoiled milk in a closed container lasts longer.Boiled milk in a closed container lasts longer because boiling kills microbes and a closed container prevents entry of new microbes. ACTIVITY 2Learn from your guardians or elders to make gundruk. Why does gundruk last longer? Discuss with friends. Synthetic or chemical food preservativesIndustrial chemistry has discovered a few chemical compounds that can kill microbes and preserve food. Such chemicals are synthesized artificially in industries. These chemicals are very effective against microbes. Very little amount of chemical food preservatives can preserve large quantities of food. The industrially prepared chemical substances which are mixed in food to prevent microbial activities and prevent spoilage are called chemical food preservatives. The food preserved using chemical food preservatives can last for many years too. However, these chemical food preservatives are harmful to the human body if consumed regularly. Therefore we should not prefer food which contains chemical food preservatives. We should consume fresh food and vegetables. Chemical food preservatives usually put into food are benzoic acid and its salts, Sulphuric acid and its salts, Sodium nitrate, Potassium nitrate, Sorbic acid, Calcium propionates, Sodium propionates, Propionates of lactic acid, Methyl or propyl Para hydroxy benzoates, Sodium diacetate, Sulphur dioxide, etc. Most of them are already banned because of their harmful side effects on our health. Figure of bakery items, breads, processed meat etc. that can possibly contain synthetic preservativesImportance of synthetic food preservatives i. These chemicals are used to preserve food in large quantities. Food can be preserved, stored and distributed during famine.ii. Many packaged foods, junk food, soft drinks and instant foods are available in the market.iii. Chemical food preservatives protect agricultural harvest so that farmers are not at risk of loss of their products. iv. Many medicines are also preserved using these chemicals. Adverse effects of synthetic food preservativesIt is allergic to some people and causes diseases like diarrhoea, cancer etc. MEMORY TIPSChemical food preservatives such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are banned in Nepal.

436 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 437FACTS WITH REASONSWe should not consume junk food frequently.We should not consume junk food frequently because it contains chemical food preservatives. If we eat junk food frequently there will be more chemical food preservatives in our body and it will make us sick. ACTIVITY 3Observe the labelling of various food products and make a list of a few food preservatives used in them. Food preservatives for induced fruits ripeningFruits ripen naturally in plants but they decay faster as well. Since farmers have to supply fruits in the market periodically, they pluck green fruits and store them. They ripen fruit artificially when they have to sell it. Traditionally farmers ripen fruits by keeping fruits in sacks, hay, malabar nuts etc. and keep them in a warm and dry room or pot or hole in the ground for a few days. Lately, farmers have been attracted to ripening fruits using industrial chemicals. Mostly calcium carbide (CaC2) is used for ripening fruit. When calcium carbide is sprayed into food, it reacts with air to produce ethylene gas. The calcium carbide, ethylene gas, ethephon etc. ripen the fruit faster in a large quantity. Therefore farmers are using them a lot. The industrial chemicals such as calcium carbide that are used to artificially ripen fruits are called food preservatives for induced fruit ripening. However, these chemicals that are used for ripening fruits have harmful side effects. First of all, fruits do not have natural sweetness and smell. When consumed they can cause diarrhoea, skin rashes, red blisters in the skin, lung problems, eye irritation, cancer, skin burn etc.Therefore, for public health, the government has already banned the use of such industrial fruit-ripening chemicals. Production, import, distribution and use of calcium carbide is illegal. We should never use such chemicals for ripening fruits. We should avoid eating fruits that are ripened using calcium carbide, ethylene gas etc. FACTS WITH REASONSWe should not consume fruits ripened using calcium carbide.We should not consume fruits ripened using calcium carbide because it can cause serious health problems such as skin irritation, allergy, lung problems, eye irritation etc. ACTIVITY 4How do people ripen bananas traditionally in hilly regions? Discuss with elders in your family. Fig: fruits that are ripened from calcium carbideMEMORY TIPSIf the fruit does not have a natural smell, then it is probably ripened using calcium carbide.

436 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 437AntioxidantOxygen present in the air is also responsible for food spoilage. If vitamin C and Vitamin E are mixed in the food, foods will not lose colour and last longer. These chemicals prevent oxidation. The chemicals that prevent oxygen from coming in contact with foods and prevent spoilage are called antioxidants.FACTS WITH REASONSJunk food with lots of antioxidants should not be eaten. Junk food with lots of antioxidants should not be eaten because it can cause prostate cancer. ACTIVITY 5What natural substances can be used as an antioxidant to preserve food? Find out.Chemical PesticidesAgriculture 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 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. The pesticide Management Act 2076 defines pesticides as \" The organic, vegetation, biological and chemical materials which is used to protect plants, agricultural products, forest, forest proeucts, living beings, livestock, human health, storage, packaging and construction works from any harmful diseases, insects, mites, nematode, weed, grass and rodents. 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 MEMORY TIPSVitamin C present in lemon is also an antioxidant. Fig: vitamin C Fig: vitamin EMEMORY TIPSNepal government started to use DDT in Nepal in 1952. They used it to kill mosquitoes. They wanted to get rid of malaria. Recently it has been recorded that Nepalese use pesticides at the rate of 396 grams per hectare per year. Most of the pesticides, almost 80%, dissolve in rainwater and mix into the river, land and environment.

438 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 439for storing, transporting and using these chemicals.Fig: pesticidesTypes of pesticides1. On the basis of impact on environment:Pesticides can be classified into two groups based on impact on environment. They are as biodegradable and non-biodegradable pesticides. a. Biodegradable pesticidesBiodegradable 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, Nygard, Rogerb. 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 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), aldrin, dieldrin, chlordane, linden, endosulfan, methoxy chloride2. 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. InsecticidesThe 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. HerbicidesHerbicides are poisonous chemicals that are usually used to kill undesired plants.Examples, metribuzin, isoproturon, atrazine, butachlor, etc.

438 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 439c. RodenticidesRodents 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. BactericidesBacteria 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. FungicidesMucor, 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. LarvicidesThe 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 actiona. 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 weeds when it is sprayed on the herbs. Examples, DDT, malathion, etc.b. Systemic pesticidesSystemic 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, biomultineem, carbamates, neonicotinoid, etc. c. Stomach pesticidesThe toxic chemicals that must enter the body through the mouth into the digestive system are called stomach pesticides (internal pesticides). They can kill the animals when consumed. It can cause headaches, nausea, diarrhoea, etc. Examples, lead arsenate, malathion, fenvalerate, cypermethrinMEMORY TIPSSystemic pesticides are very dangerous because they cannot be removed from vegetables even by washing. It cannot be removed from vegetables by washing because it is present inside the tissues of vegetables. Therefore we should not consume vegetables for a week after using systemic pesticides.

440 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 441d. Fumigant pesticidesThe 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 originBased 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). Precaution regarding pesticides:While purchasing:i. Buy, import, trade or purchase the pesticides as allowed by the “Pesticides Management Act 2076. ii. Buy the pesticides as prescribed by agricultural technicians only.iii. Do not buy Group IB pesticides. While storing:i. We should always store in original containers. ii. The label should not be removed.iii. It should be airtight and leakage-proof.iv. It should be stored far away from children, teenagers, animals, water, food, bedroom and kitchen. FACTS WITH REASONSAgrichemicals such as chemical pesticides and chemical fertilizers should be transported separately from people, water and food products. Agrichemicals such as chemical pesticides and chemical fertilizers should be transported separately to prevent contamination of food products, water and people. ACTIVITY 6How should we dispose of the containers of poison? Discuss with friends. Precaution while using pesticidesi. Use good pesticides that are less toxic but effective.ii. We should be very careful while transporting and using.iii. We should not wash pesticide containers and other tools used for spraying near the water resources.iv. Use limited quantity only. MEMORY TIPSDDT, BHC, aldrin, dieldrin, linden, chlordane, endosulfan, etc. are banned in Nepal.

440 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 441v. Use an apron, gloves, gas mask and goggles while using pesticides. vi. We should bath properly and wash clothes as soon as possible after using pesticides. vii. Do not use vegetables for a few days after using pesticides. viii. We should use integrated pest management methods. The use of all available techniques such as biological, chemical, physical and crop-specific pesticides to prevent the rise of the population of pesticide resistance pests is called Integrated pest management.Poisonous chemicals used in homesPesticides 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. Hydrochloric acid is used to clean marble and kitchen tiles. Chlorine is added to water tanks and sewage to kill microbes. Fig: acid used to clean basin Fig: chlorine to purify water Fig: mosquito repellentFACTS WITH REASONSChlorine is mixed in sewage. Chlorine is mixed in sewage because it can kill microbes by producing acid when it dissolves in water. ACTIVITY 7What kinds of poisonous chemicals are used in the house? Discuss. Chemicals used in cleaningVarious natural ingredients have traditionally been used for cleaning the body, hair, face, clothes and utensils for ages. However, very effective modern synthetic cleansers are also being used for cleaning nowadays. Broadly cleansing agents are divided into traditional and modern cleansers. MEMORY TIPSAcid can clean marbles because acid is corrosive.

442 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 443Traditional (natural) cleansing agentsNaturally available materials such as fruits, seeds, leaves and oil are traditionally used for cleaning. Reetha (soapnut), wooden ash, mustard peena, sajiban and lemon juice are some natural ingredients that have been used traditionally for ages. ReethaReetha contains a chemical called saponin. The saponin has a cleaning capacity. So, it has been used to clean hair, body and clothes for ages. It is used as a foaming agent in shampoo as well. It is believed that it can make hair shiny and long. Wooden ashWhen the wood is burned it produces wooden ash. It contains nutrients for plants such as potassium, magnesium and phosphorus. So, it helps in disease resistance, formation of chlorophyll and development of the root system. If it is mixed with water it can clean stains and oils from utensils and clothes. Mustard PeenaMustard peena contains vitamin B complex in various forms such as vitamin B6, folate, niacin and thymine. Vitamin B complex is very good for hair. It makes the roots of hair strong and prevents hair fall. It removes dandruff. It is mixed with water to form a paste. The paste is used to wash hair. It makes hair strong, long and shiny. SajeevanSajiban is a very useful plant. It is used in medicine, composting, cleaning and fuel. It is used as medicine to treat skin diseases, kill lice, oil massage joints and muscles to relieve pain and make anticancer medicine. It is also used for composting because it is rich in primary nutrients (NPK). Its twigs are used for cleaning teeth and its oil can be used to make soap and glycerine. Its oil can be used as fuel for vehicles. So its oil is called bio-diesel. 3 kilograms of sajiban seed can give a litre of oil because these seeds are very rich in oil. The seed contains 30 to 40 % oil. Lemon juiceLemon is a citric fruit. Many people drink lemon juice for good health. It contains citric acid. Citric acid is a weak acid. It is corrosive due to which it can remove rust and stains. Since lemon juice is acidic it kills germs too. It has antimicrobial properties. So, it is commonly used to wash dishes, clean metal parts and clean tiles. Importance of natural cleansing agentsi. They do not have side effects.ii. They are less toxic to humans.iii. They do not pollute the environment. Modern (synthetic) cleansing agentsNatural cleansing agents are less effective and inconvenient for cleansing purposes. Hence, people are more attracted to the use of synthetic cleansers. Colin, phenol, soap, shampoo, nail polish remover, detergent etc. are the most common synthetic cleansers. Synthetic cleansers can make clothes, marbles, garments, utensils, tiles etc. clean easily and effectively however they are bad for the environment.

442 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 443SoapSoap 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 with sodium hydroxide or potassium hydroxide. The process by which soap is prepared is called saponification. During saponification, sodium chloride is added in the solution to bring the soap in precipitation because sodium chloride increases the ionic product and decreases the solubility product. Soap having less density floats on the surface of the solution. Now it is collected and kept into moulds to get the soap cakes. Sodium carbonate or starch is added to make the soap hard. Different types of perfumes, colors, antiseptics and bleaching materials are also added in the soap.DetergentsDetergents are synthetic petrochemicals obtained from hydrocarbons which are more soluble than soap. For example: Sodium lauryl sulphate, alkyl benzene sulphonate, sodium pyrophosphate, etc.Detergents are sodium salts of long chain benzene sulphonic acid, which are mostly nonbiodegradable with more cleansing property. A detergent is one of the cheap and popular cleansing agents made from hydrocarbons of petroleum by-products.Detergent is also called soapless soap because it has cleansing property like a soap but does not contain the chemicals that are found in the soap. Detergents are better than soap because they can change hard water into soft water and produce a lather. It can remove stains easily from clothes. Differences between Soaps and DetergentsS.N. Soaps S.N. Detergents1 Soaps are biodegradable cleansing agents.1 Detergents are non-biodegradable cleansing agents.2 It cannot be used with hard water. 2 It can be used with hard water.3 Soap is made by boiling a mixture of animal fat or plant oil with sodium hydroxide.3 Detergent is made by boiling petroleum byproducts with sodium hydroxide.Effects of excessive use of detergentsDetergent is a non-biodegradable chemical substance. It is harmful to the environment and human health. It remains in soil and water for a very long time. It harms the environment. It pollutes land and water, disturbs aquatic life and disturbs the normal growth of plants. It is harmful to human health as well. It can cause skin burns. It can damage the skin of the hands and fingers while washing clothes. It is also noted that it discolours the clothes.

444 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 445Chemical PollutionThe pollution created by unwanted and excessive use of chemical substances is called chemical pollution. The different types of useful and useless chemicals which are obtained from organic and inorganic substances like fertilizers, insecticides, soaps, detergents, plastics, fibers, etc. are polluting the environment everyday. So, contamination by unwanted chemicals in the environment is called chemical pollution. Causes of chemical pollutionVarious factors are directly and indirectly involved in chemical pollution. Among them, some major factors are: i. The use of insecticides and fertilizers : Chemical fertilizers and insecticides constitute major chemical pollutants. These chemicals cause water, air and soil pollution. Most of them are non-biodegradable, so their effect remains for a long time. Insecticides like DDT cause water, air and soil pollution. Our environment has also been polluted by toxic insecticides like aldrin, dieldrin and heavy metals like lead, cobalt, mercury, etc. Nitrogenous fertilizers, when washed by rainwater, reach the water body. Due to the presence of nitrogen element, aquatic plants develop more rapidly and reduce oxygen concentration of water. Thus, aquatic animals die due to more BOD (Biological Oxygen Demand) value. ii. Household wastes and plastics : Different types of solid wastes of food, vegetables, clothes, ceramics, detergents, soaps, plastics, etc. also cause chemical pollution. The non-biodegradable nature of some chemicals like plastics, detergents, etc. is creating a severe problem in the environment. So, it is necessary to recycle plastics in order to avoid pollution by plastic materials. The degradable waste produces bad smell, spread germs, spread house flies etc. Mixing of degradable waste in water is also harmful. Microbes start aerobic decomposition of waste. So, amount of oxygen decreases in the water. It harms aquatic animals and plants.FACTS WITH REASONSEnvironmentalists call for avoiding the use of plastics. Why?Plastic is a non-biodegradable substance which remains on the earth's surface for a long time without decomposing. When plastic is thrown everywhere, it causes environmental pollution. When plastics are burnt, they emit poisonous gases which affect the health of living organisms. So, environmentalists have called for avoiding the use of plastics. iii. Smoke from vehicles and factories : The products of combustion like carbon dioxide, carbon monoxide, sulphur trioxide, etc. are the major air pollutants. These gaseous pollutants come from industries and vehicles. When these gases combine with water, they give different types of acids like sulphuric acid, nitric acid, carbonic acid, etc. They come down in the form of rain called acid rain. Acid rain Smoke from industries

444 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 445damages plants, animals, soil, etc. Carbon dioxide, methane, ozone, etc. also result in the greenhouse effect, which ultimately causes global warming. iv. Coloring materials of foodstuff : Various chemical food colours are used in food products, sweets and soft drinks. All the colors are made from chemical compounds. Most of these compounds harm our health directly or indirectly and cause short-term or long-term effects. v. Dyes and detergents : Dyes like peroxide, hypochloride, sodium hydroxide and other bleaching agents, which are released from different industries like leather, textile, carpet, etc. also cause chemical pollution. They destroy the natural quality and composition of water. Detergent is another non-biodegradable cleansing agent, which remains in water for a long time and makes water unsuitable for drinking. vi. Metallic particles : Automobiles and industries release different types of metallic particles like lead, chromium, cadmium, mercury, arsenic, etc. When human beings, animals, birds and fishes inhale these metals, directly or indirectly, they suffer from various diseases. Ways to Get Rid of Chemical Pollution Plastics are the main agents of chemical pollution. We should use chemical fertilizers only after testing soil. The waste materials produced from industries and automobiles should be disposed properly. The harmful gases released from industries and automobiles should be changed into harmless gases before releasing them into the atmosphere. Household biodegradable wastes should be used to produce compost manure. We should be careful while using insecticides and pesticides. We should use edible colors in food items. These activities help to reduce environmental pollution caused by different chemical substances. Waste materials such as industrial chemicals should be managed by municipality. For example, waste such as glass pieces, wood pieces, metal scraps, containers, plastics, cement, fertilizer waste, sewage, etc. should be properly managed by the municipality. There should be a facility for the collection, separation, reuse, recycling, composting, incinerating and dumping of waste in the municipality.Environmental impact of dichloro diphenyl trichloroethane(DDT)i. Loss of fish in rivers, a decrease in the number of birds in forests, birds laying thin eggs are ii. remains in land and water for a very long time, kills useful species and disturbs the ecosystem. iii. kills people, disturbs the reproduction of animals

446 ChEmiCals usEd in daily lifE Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 447HOT SKILL HIGHER ORDER THINKING SKILL1. Many people use the swimming pool every day. They can spread germs in the pool. How is the pool kept clean and germ-free? Many people use the swimming pool every day. It is likely to have lots of germs. The pool must be kept clean and germ-free. The following methods are used to kill germs:i. Water is pumped through a filter to remove solid wastes.ii. Chlorine is added to get rid of algae and bacteria. Chlorine is frequently added to swimming pools because it reacts with water to create an acid that can eradicate bacteria, protists, and other microorganisms.2. In case, soap and detergent are not available, World Health Organization has suggested that people should use wood ash as a cleaning agent. Why?In case, soap and detergent are not available, people are suggested to use wood ash as a cleaning agent by WHO. The reason is it is antibacterial. It also produces lye (sodium hydroxide). It can be used to wash hands and dishes. 3. Ramesh has a vegetable farm. Due to the lockdown, he could not sell his vegetables such as spinach, radish etc. What can he do to prevent food spoilage?Ramesh has a vegetable farm but he could not sell it due to the lockdown. To prevent food spoilage, he can do the following things. i. Vegetables can be stored in a refrigerator or cold storage. ii. Vegetables can be sliced into tiny pieces, dried and stored.iii. Vegetables such as radishes, tomatoes, cauliflower and mushroom can be pickled.iv. Green vegetables can be dried and stored or pickled. 4. Antioxidants are effective to preserve food. However, countries such as Australia, Canada and Japan have banned BHA antioxidants. Antioxidants are very effective to preserve food but it is banned in many countries. For example, BHA antioxidant is banned in Australia and Japan. The reason is some antioxidants are harmful to human health:i. It can cause faster ageing. ii. It can cause cancer. iii. It can be allergic to some people. 5. Farmers dry their wheat and paddy in sunlight. Farmers dry their wheat and paddy in sunlight because it removes moisture. When moisture is removed the grains can last for a very long time. 6. The Nepal government has controlled the import, production, storage, and distribution of pesticides. Pesticides are not medicines. They are poison. Pesticides can cause cancer to farmers and food consumers. Pesticides can immediately kill people, local animals, and insects. It hurts the ecosystem. Pesticides can pollute land and water resources. It can cause health problems. Since these poisons are very dangerous for life and the environment, the government regulates their import, storage, production and distribution to protect people, wildlife and the environment from the harmful effects of pesticides.