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2. CHAPTER VII – Non Metals Science – IX

3. Module Objectives • Recap – How elements are classified and arranged into periodic tables. • Non-metals examples • List out the physical properties of non-metals • Write the chemical properties of non-metals • Distinguish between metals and non-metals • Study of two important non-metals – 1. Phosphorous 2. Sulphur, which are used widely.

4. Phosphorous • Essential nutrient and components of bones, teeth, gums and blood of animal body. • Necessary for the growth of the plant and to carry out photosynthesis in plants • It is the second element of 15th group in periodic table • SYMBOL – P • ATOMIC NO. – 15 • MASS NO. – 31 • Electronic Configuration – 1s2,2s2,2P6, 3S2,3P3

5. Phosphorous - Occurrence • Highly active element • Does not occur freely in nature • Widely distributed in nature in phosphate rocks • It is main component of bone. So, it occurs in bone ash in the form of calcium phosphate • Important minerals of Phosphorous. • Note – Apatite is also known as Fluorapatite

6. Phosphorous - Extraction • Extracted by heating bone ash or rock phosphate • Mixture of finely powdered rock phosphate, sand (silica) and coke are introduced in electric furnace • An electric arc struck between the electrodes produces high temperature • Phosphorous pentoxide is formed by the reaction of rock phosphate and sand (silica)

7. Allotrophicforms of Phosphorous • Like carbon, phosphorous also exhibits allotropy. • Two allotropic forms are white phosphorous and red phosphorous • White phosphorous is obtained by rapid cooling of phosphorous vapour. • Red phosphorous is prepared by heating white phosphorous to about 2500C along with inert gases

8. Allotrophicforms of Phosphorouscontd. • When white phosphorous is exposed to air at about 300C, it reacts with oxygen and fumes • But, it does not react with water • So this highly reactive element is stored under water • White phosphorous undergoes spontaneous slow oxidation in air • This oxidation is visible like a greenish glow in the dark. This phenomenon is known as Phosphorescence.

9. Phosphorous – ChemicalpropertiesAction with AIR / OXYGEN • Phosphorous trioxide is formed when phosphorous is burnt in a limited supply of air. • Phosphorous pentoxide is formed when phosphorous is burnt in excess of air.

10. Phosphorous – ChemicalpropertiesAction withChlorine • Phosphorous trichloride is formed when the supply of chlorine is limited. • Phosphorous pentachloride is formed with excess amount of chlorine

11. Phosphorous – ChemicalpropertiesAction with Alkalis • Phosphine is formed when phosphorous is boiled with Sodium hydroxide • Phosphine is a colorless gas with an unpleasant odour. It is highly poisonous • Oxides of phosphorous are acidic in nature. They form oxyacids when they disolve in water. • Important oxyacids are: • Orthophosphoric acid – H3PO4 • Metaphosphoric acid – HPO3 • Pyrophosphoric acid – H4P2O7

12. Uses of Phosphorous • Red Phosphorous is used widely in the manufacture of safety matches • White phosphorous is used in bullets and in incendiary bombs • It is used to make phosphorous bronze • Phosphorous is used in rat poison • It is widely used in the manufacture of phosphate fertilizers

13. Phosphorousfertilizers • Essential for the growth of plants • Needed to carry out photosynthesis and to give high yield • Plants absorb phosphorous in the form of water soluble compunds • Leaves turn yellow when they do not get phosphorous in the required quantity • So, it is necessary to add phosphorous in the form of chemical fertilizer to soil

14. Preparation of Super Phosphate • Manufactured by treating the water insoluble phosphate rock with a specific amount of concentrated sulphuric acid • Mixture of Calcium sulphate and calcium dihydrogen phosphate is obtained. This mixture is called super phosphate

15. Sulphur • Element sulphur has been known from ancient times as Brimstone which means Burning Stone • Brimstone means burning stone. • Sulphur is used in the treatment of skin diseases and as a fumigant since ancient times. • Symbol – S • Atomic No. – 16 • Atomic Mass – 32 • Electronic configuration – 1S2, 2S2, 2P6, 3S2, 3P4 • Sulphur is second element of 16th group in the periodic table • Due to its incompletely filled outer orbit (3S2, 3P4) it readily combines with other elements forming covalent and ionic bonds.

16. Occurrence of Sulphur • Sulphur is highly reactive element. • Occurs in free state and more abundantly as a compound. • It occurs in free state as vapour in volcanic eruption • Main Sulphur ores • Galena – PbS • Cinnabar – HgS • Zinc blende – ZnS • Gypsum – CaSO42H2O

17. Extraction of Sulphur • Sulphur is obtained from underground deposits by Frasch process • Method is based on the relatively low melting point of sulphur (1190C) • Sulphur deposits occur at a depth of about 230 to 400 metres.

18. Extraction of Sulphur • Concentric pipes are sunk from the surface to the sulphur deposits • Super heated water at 1700 – 1800C is sent through the outer most pipes • Same time, hot compressed air is forced down through the central pipe • Hot water melts sulphur • Foam is produced which it mixes with hot air • Foam is brought up to the surface by middle pipes by the action air blast • Sulphur obtained is about 99.5% pure.

19. Allotropicform of Sulphur • Exhibits allotropy like carbon and phosphorus • Allotropes of sulphur are Rhombic sulphur, monoclinic sulphur and plastic sulphur

20. RhombicSulphur • Powdered Sulphur is dissolved in carbon disulphide to make a saturated solution. • It is allowed to evaporate slowly • Yellow crystals of rhombic sulphur are obtained • Eight atoms are arranged in octahedral shape • Hence, it is also called as Octahedral sulphur

21. MonoclinicSulphur • Monoclinic Sulphur which is also known as Prismatic Sulphur or beta-Sulphur, is a yellow crystalline solid • Take sulphur in China dish and melt it slowly at 1250C • Allow liquid to cool slowly until a crust is formed at the surface • Break the crust and pour the liquid only • Observe crystals of needle-shaped monoclinic sulphur sticking to the sides of dish. This is called Prismatic sulphur • Rhombic sulphur is stable below 950C while monoclinic is stable above 95.50C • When Rhombic sulphur is heated above 95.50C monoclinic sulphur is formed

22. Plastic Sulphur • Melt sulphur in china dish and molten Sulphur is poured in cold water • Soft rubber like mass is obtained • Dark-brown elastic solid is called Plastic sulphur

23. Effects of heat on Sulphur • When Sulphur is heated above 1150C it melts and a pale-yellow liquid is obtained • At 1800C the liquid becomes dark brown and viscous and does not flow • Ring structure is changed into open chain • High temperature the chain breaks down • At about 4350CSulphur boils and its vapour is formed

24. Physicalproperties of allotropes of Sulphur

25. ChemicalProperties • Sulphur burns within limited supply of air with a blue flame to give sulphur dioxide along with small quantity of sulphur trioxide • Sulphuric acid is formed when sulphur trioxide dissolves in water

26. Reactionwithnon-metals • Sulphur forms sulphides with other non-metals • When sulphurvapour is passed through red-hot coke, carbon disulphide is formed C + 2S  CS2 • When hydrogen gas is passed through molten sulphur, hydrogen sulphide is formed H2 + S  H2S • When sulphur reacts with concentrated nitric acid, sulphuric acid is formed S + 6HNO3 H2SO4 + 6NO2 + 2H2O

27. Uses of Sulphur • Sulphuris mainly used for the manufacture of Sulphuric Acid • It is good disinfectant and used in manufacture of skin ointments • Vapours of lime and sulphur are used as insecticides • Sulphur is the main component of gunpowder and explosives • Used for vulcanising natural rubber

28. Vulcanisation • Natural rubber is a polymer of long chain hydrocarbon • Becomes sticky when heated and brittle when cooled • Because of its elasticity, it is not possible to give definite shape to rubber • When sulphur is added in a definite proportion to the natural rubber, it becomes hard and gets all the desirable properties • It is easy to give it any definite shape

29. Combustion • Production and regulation of fire changed the life of ancient man remarkably. • Early man found that he could keep himself warm with fire, cook food to make it more tasty • He used fire to extract metals, to make bricks etc. • Hence, Use of fire has played a vital role in the development of civilisation • Combustion is a type of chemical change • Even today, man depends upon combustion to meet his major energy requirements

30. Whatis Combustion? • When substances (mainly fuels) react with oxidizing agents like oxygen, produce energy in the form of heat and light, this process is called Combustion • Combustion is a type of chemical change in which energy is liberated and new substances are formed

31. Types of Combustion • Crackers undergo combustion very quickly liberating enormous amount of energy in the form of light and heat. This is know as explosion Note the following chemical reactions • Rusting of iron, that is action of moist air with iron to produce iron oxide • Oxidation of glucose by oxygen in our body. • Above said reactions are examples of Combustion which take place very slowly

32. Calorific Value • Earlier, heat energy was measured in calories. • Now, heat energy can be converted into mechanical energy • Hence, heat energy is also expressed in Joules

33. Carbonic Fuels • Carbonic fuels are the main sources of energy • Coal and petroleum are main carbon fuels

34. Carbonic Fuels - Petroleum • Petroleum is a complex mixture of many saturated hydrocarbons • These hydrocarbons have carbon atoms ranging from 4 to 50 • Crude oil and natural gas mixture are obtained from the mines • After separating natural gas the crude oil mixture is subjected to fractional distillation to separate different fractions

35. ComparisonbetweenPetrol & Diesel

36. Caution • Petroleum fuels are non-renewable sources of energy • They were formed over the cours of millions of years in the earth’s crust • Petroleum is important source of energy • Technology of utilising alternate economical sources of energy has not yet been developed

37. Combustion and air pollution • Atmosphere is the thin blanket of air around the earth • It sustains life on the earth • Major components of pure air are nitrogen, oxygen, carbon dioxide, rare gases and traces of water vapour • Air is polluted when unwanted substances enter into the atmosphere and cause ill effect on Biotic and Aboitic environment • Air pollution is principally caused by gases produced combusion

38. Effect of air pollution on Biotic and Abioticenvironment • Carbon dioxide • Even though carbon dioxide is an essential component of air, if the percentage of the gas increases above a certain limit, it causes pollution. • When the percentage of carbon dioxide increases, it checks the heat radiations produced by Earth which results in increase of global temperature • Carbon monoxide • Produced by the partial combustion of carbon fuel • On inhaling air containing carbon monoxide, it combines with hemoglobin of red blood corpuscles forming carbon-hemoglobin. Then it reduces the oxygen carrying capacity of blood • Hydrocarbons • 55% of the hydrocarbons present in the atmosphere are formed due to incomplete combustion of petroleum fuels • Responsible for the smog formation in atmosphere

39. WhatisAcidRain? • Oxides of Nitrogen and Sulphur • Oxides of nitrogen and sulphur are produced by the combustion of petroleum products and coal which cause Acid Rain • Oxides of sulphur and nitrogen combine with the water vapour in the atmosphere to form sulphuric acid and nitric acid • These acids precipitations dissolve in rain water known as Acid Rain • Acid rain causes extensive damage to stone buildings and sculpture of marbles, limestone, etc • Stones become pitted and weaken mechanically.

40. Lead & otherpollutants • Lead is added to petrol in the form of tetra ethyle lead for the efficient working of engines • It comes out of the engine along with exhaust gases • Lead causes brain disorder in human beings Other pollutants • Dust and carbon particles produced due to incomplete combustion and fly ash are also responsible for air pollution • They affect the health of living beings • They spoil the beauty of buildings

41. References • http://educationalelectronicsusa.com/c/metals-VI.htm • Google Images • http://www.wisegeek.org/

42. Exercises