Sodium Oxide (Na2O)

Group - I & II Oxides Sodium Oxide Preparation : 1. By burning sodium at 180'C in a limited supply of air or oxygen and distilling off the excess of sodium in vaccum. 2Na + 1/2 O2 --180'C--> Na2O 2. By heating sodium peroxide, nitrate or nitrite with sodium Na2O2 + 2Na ---> 2Na2O 2NaNO3 + 10Na --> 6Na2O + N2 3. Sodium oxide is formed when the mixture of sodium azide and sodium nitrite is heated. 3NaN3 + NaNO2 --> 2NaNO3 + 5N2 Chemical Properties : 1. It is white amorphous substance. 2. It decomposes at 400'C into sodium peroxide and sodium. 3. It dissolve violently in water, yielding caustic soda (NaOH) and evolving a large amount of heat. Na2O + H2O --> 2NaOH Uses : It is used as dehydrating and polymerising agent in organic chemistry.

SODIUM PEROXIDE (NA2O2)

SODIUM PEROXIDE (Na2O2) Preparation : 1. By heating the metal in excess of air or oxygen at 300', which is free from moisture and CO2. 2Na + O2 (excess) --> Na2O2 2. Industrial method : It is a two stage reaction in the presence of excess air. 2Na + O2 --> Na2O Na2O + O2 --> Na2O2 Properties : 1. It is a pale yellow solid (when impure), becoming white in air from the formation of a film of NAOH AND NaCO3. 2. In cold water (~0'C) produces H2O2 but at room temperature produces O2. In ice cold mineral acids also produces H2O2. Na2O2 + 2H2O --> 2NaOH + H2O2 2Na2O2 + 2H2O --> 4NaOH + O2 Na2O2 + H2SO4 --> Na2SO4 + 2H2O +O2 3. It reacts with CO2, giving sodium carbonate and oxygen and hence its use for purifying air in a confined space e.g. Submarine, ill ventilated room. Na2O2 + CO --> Na2CO3 4. It is an oxidizing agent and oxidises charcoal, CO, NH3, SO2. 3Na2O2 + 2C --> 2Na2CO3 + 2Na [ deposition of metallic Na ] CO + Na2O2 --> Na2CO3 SO2 + Na2O2 --> Na2SO4 5. It contains peroxide ion [-O-O-]^-2 and it react with C6H5COCl formed benzoyl peroxide (BLEACHING agent ). So it acts as a powerful oxidising agent. a. Chromic compounds are oxidised to chromates. b. Manganous salt is oxidised to sodium mangamate. c. Sulphides are oxidised to corresponding sulphates

Oxides of Potassium

Potassium oxide Preparation : 1. By heating potassium nitrate with potassium nitrate with potassium. 2KNO3 + 10K --> 6K2O +N2 Potassium peroxide (K2O2) Preparation : By burning potassium at 300'C in a limited supply of air or oxygen. 2K + O2 --> K2O2 POTASSIUM Superoxide (KO2) Preparation : i. Passage O2 through a blue solution of K in liquid NH3 yields oxides K2O2, K2O3 , KO2 reacts with H2O and produces H2O2 and O2 both. ii. It is prepared by burning potassium in excess of oxygen free from moisture. K + O2 --> KO2 POTASSIUM SESQUIOXIDE (K2O3) preparation : It is obtained when oxygen is passed through liquid ammonia containing potassium . 4k + NH3 --> 2K2O3

Short Info : Magnesiun Oxide (MgO)

Magnesium Oxide (MgO) It is also called as milk of magnesia. Preparation : It is also called magnesia and obtained by heating natural magnesite. MgCO3 --^--> MgO + CO2 Properties : 1. It is white powder. 2. Its m.p is 2850c . Hence used in manufacture of refractory bricks for furnaces. And it is acts as basic flux and facilitates the removal of acidic impurities of Si, P, and S from steel through slag formation. 3. It is very slightly soluble in water imparting alkaline reaction.

Calcium Oxide (CaO)

Preparation : It is commonly called quick lime and made by decomposing line stone at a high temperature about 1000"C. CaCO3 --> CaO + CO2 + 42000 cal. Chemical properties : 1. It is white amorphous powder of m.p 2570 c. On exposure to atmosphere ; it absorbs moisture and carbon dioxide. CaO + H2O --> Ca(OH)2 CaO + CO2 --> CaCO3 2. It emits intense light (lime light), when heated in oxygen-hydrogen flame. 3. It combines with limited amount of water to produce slake lime. This process is called slaking of lime. Quick line slaked with sofa gives solid sodalime (CaO ). Being basic oxide. CaO + H2O --> Ca(OH)2 4. Soda lime (basic oxide) combines with some acidic oxides at high temperature. CaO + SiO2 --> CaSiO3 6CaO + S4O10 --> 2Ca3(PO4)2 CaO + CO2 --> CaCO3 Uses : i. It is an important primary material for manufacturing cement and is the cheapest form of alkali ii. It is used in the manufacture of sodium carbonate from caustic soda iii. It is employed in the purification of sugar and in the manufacture of eye stuffs Magnesium peroxide and Calcium peroxide : These are obtainned by passing H2O2 in a suspension of Mg(OH)2 AND Ca(OH)2 Uses : MgO2 is used as an antiseptic in tooth paste and as a bleaching agent.

Sodium Hydroxide ( Caustic Soda ) NaOH

Sodium Hydroxide also known as Caustic Soda (NaOH) Preparation : i. Electrolysis of Brine : Sodium hydroxide is generally prepared commercially by the electrolysis of sodium chloride in Castner-Kellner cell. A brine solution is electrolysed using a mercury cathode and a carbon anode. Sodium metal discharged at the cathode combines with mercury to form sodium amalgam. Chlorine gas is evolved at the anode. The amalgam is treated with water to give sodium hydroxide and hydrogen gas. Cathode : Na+ + e- --Hg--> Na-amalgam Anode : Cl- --> 1/2 Cl2 + e- 2Na-amalgam + 2H2O --> 2NaOH + 2Hg + H2 2. Caustication of Na2CO3 (Gossage method) Na2CO3 + Ca(OH)2 --> 2NaOH + (suspension) CaCO3 Ksp (CaCO3) < Ksp (Ca(OH)2), the reaction shifts towards right. Properties : 1. Sodium hydroxide is a white, translucent solid. It melts at 591 K. It is readily soluble in water to give a strong alkaline solution. Crystals of sodium hydroxide are deliquescent. The sodium hydroxide solution at the surface reacts with the CO2 in the atmosphere to form Na2CO3. 2. It is white crystalline, deliquescent, highly corrosive solid. 3. It is stable towards heat. 4. Its aqueous solution alkaline in nature and soapy in touch. 5. Acidic and amphoteric oxides gets dissolved easily 6. Aluminium and Zn metals hues H2 from NaOH. 7. Several non metals such as P, S, Cl. Yields a hydride instead of hydrogen Uses : It is used in i. The petroleum refining. ii. The manufacture of soap, paper, Artificial silk and a number of chemicals. iii. In the purification of bauxite iv. In the textile industries for mercesing cotton fabrics. v. For the preparation of pure fats and oils vi. As a laboratory reagent.

Potassium Hydroxide (KOH)

Preparation : It is prepared by electrolysis of KCl solution. Uses : 1. KOH resembles NaOH in all its reactions. However KOH is much more soluble in alcohol. This accounts for the use of alcoholic KOH in organic chemistry. 2. KOH is called caustic potash , because of their corrosive properties (for example on glass or on skiny) and its aqueous solution is known as potash lye. 3. It is used for the absorption of gases like CO2, SO2 etc., It is used for making soaps. Properties : Everything is as same are NaOH just replace Na, NaOH with K, KOH 1. Sodium hydroxide is a white, translucent solid. It melts at 591 K. It is readily soluble in water to give a strong alkaline solution. Crystals of sodium hydroxide are deliquescent. The sodium hydroxide solution at the surface reacts with the CO2 in the atmosphere to form Na2CO3. 2. It is white crystalline, deliquescent, highly corrosive solid. 3. It is stable towards heat. 4. Its aqueous solution alkaline in nature and soapy in touch. 5. Acidic and amphoteric oxides gets dissolved easily 6. Aluminium and Zn metals hues H2 from NaOH. 7. Several non metals such as P, S, Cl. Yields a hydride instead of hydrogen Some new properties 1. It is stronger case compared to NaOH. 2. Solubility in water is more compared to NaOH. 3. In alcohol, NaOH is sparingly soluble KOH is highly soluble . 4. As a regent KOH is less frequently used but in absorption of CO2, KOH is preferably used compared to NaOH . Because KHCO3 formed is soluble whereas NaHCO3 is insoluble and may therefore choke the tubes of apparatus used.

Calcium Hydroxide (Ca(OH)2)

Name of compound : Calcium Hydroxide (Ca(OH)2) Name and brief about the process : By spraying water on quicklime. Related chemical reaction : CaO + H2O --> Ca(OH)2 Properties : 1. It is a white amorphous powder. 2. It is sparingly soluble in water. 3. Its solubility in hot water is less than that of cold water. Hence solubility decreases with increase in temperature. 4. The aqueous solution is known as lime water and a suspension of slaked lime in water is known as milk of lime. 5. When carbon dioxide is passed through lime water it turns milky due to the formation of calcium carbonate. Ca(OH)2 + CO2 --> CaCO3 + H2O On passing excess of carbon dioxide, the precipitate dissolves to form calcium hydrogen carbonate. Milk of line reacts with chlorine to form hypochlorite, a constituent of bleaching powder. 2Ca(OH)2 +2Cl2 --> CaCl2 + CaCl2 + H2O2 Uses : 1. It is used in the preparation of mortar, a build material. 2. It is used in white wash due to its disinfectant nature. 3. It is used in glass making , in tanning industry , for the preparation of bleaching powder and for purification of sugar.

Crossbred animals

1. Crossbred animals are obtained by breeding two different varieties of animals, usually one is local and other is imported. 2. Formerly this technology was used to obtain hybrid plants but now animals are also obtained through such technology. 3. The crossbred varieties are more robust and strong. 4. They can put in more work and give greater yield. Since the yield is greater, the profits are also larger. 5. An Indian cow is crossed with Jersey, Holstein or See Dean bull. The offspring obtained through such a cross gives 10 to 12 litres of milk per day as against 5 to 6 litres obtained from an indian cow. 6. Kandhari, Devani, Khilari and Dangi are the varieties of cows from Maharashtra which are usede for crossbreeding.

Complete "Soil" guide part 1

1.Soil : a. Soil provides support and nourishment to plants. b. Soil helps plants to grow. It is the base of agriculture. c. The survival of all plants and animals and their nourishment depends upon the soil. 2. Constituents of soil : Stones, pebbles, sand, fine soil particles and organic substances are the various constituents of soil. 3. Formation of soil - weathering of rocks : The process by which rocks are transformed into soil is called weathering. a. The weathering of rocks and formation of soil are affected by various element of nature. b. Changes in the atmosphereic heat and cold, winds, etc. Bring about the weathering of rocks. c. The weathering of rocks and boulders also occurs due to the effects of rivers, rainwater, winds and continuous changes in the weather. Owing to this , rocks and boulders are converted into smaller particles which ultimately form soil. 4. Biological weathering of rocks : a. Rodents like rats and bandicoots that live in burrows help in the conversion of rough earth into soil. b. Roots of the plants growing into the cracks in rocks play an important role in the weathering of rocks. The soil formed is generally clay . 5. Time : It takes about 800 to 1000 years for the formation of a 2.5 cm thick layers of fertile soil. 6. Soil - a natural resource : a. Plants life has developed on the earth owing to the presence of soil. b. Plants provide food to animals and human beings. c. Plants meet our three basic needs-food, shelter and clothing. d. Minerals and metals are also obtained from soil.

Complete "Soil" guide part 2

7. Uses of soil : a. Soil can be given any desired shape. This property of the soil is called plasticity. b. Soil nurtures plants. c. Soils holds water. d. Bricks that are used for construction work are made from the soil. e. The earthen vessels and walls of some houses are made of clay (soil). 8. Colour of the soil : a. The soil has different colours. It may be red, black, yellow, and copper coloured. b. The colour of the soil gives an idea of its fertility, drainage and other such properties. c. The colour of the soil depends upon the following constituents. i. Texture ii. Organic content and iii. Chemical substances like iron, quicklime, etc. 9. Soil also contains find particles of quartz, feldspar, nica, carbonates of metals, oxides and sulphides of iron along with the organic matter. 10. Types of soil : ( According to use ) a. There are three types of soil , viz., China clay, clay and loamy soil. b. The China clay or Kaolin is found near the Kaolin mountain in China. c. It is white in colour and is used for making crockery, tiles for bathrooms and laboratory apparatus. d. Different lines of oxides are used to decorate earthenwares or porcelain articles. For example, iron oxide is used to obtain red colour while copper oxide is used to obtain green colour. e. Loamy soil being white in colour is used to make idols and statues. 11. Types of soil : (According to texture) a. The size of soil particles decides the texture of soil. b. There are three types of soils based on the texture. There are sandy soil, clayey soil and silt. c. Sandy soil has greater proportion of fine sand. It has the least capacity for holding water. d. Clayey soil has greatest capacity for holding water. e. Silt soil consists of find to medium sized soil particles. It has medium capacity for holding water. f. The soil which holds lots of water is not well aerated.

Complete "Soil" guide part 3

12. Constituents of soil : a. Soil has constituents of both plane and animal origin. There constituents are called organic costituents. b. Constituents of plant origin include bacteria, algae, fungi, decomposed leaves of plants, etc. c. Constituents of animal origin constituttue protozoa,worms, insects, shells and decomposed remains of dead animals. 13. Soil erosion : a. The removal of top fertile layer of the soil from the soil surface is called soil erosion. b. Soil is eroded by rainwater falling on it and by east currents of water flowing on it . c. Soil is also eroded by rust of winds. d. Soil must be kept covered to prevent soil erosion. Growing grass and the cross on the land, cover the soil. e. Trees planted on the land also provide the cover. f. Soil erosion can be reducee by arranging the soil horizontally across the lines of slopes as erosion of soil depends upon the slope. g. Construction of bunds to stop the flowing water also prevents the soil erosion. 14. Soil Conservation : a. Arresting soil erosion to conserve the soil is called soil conservation. b. The government has set up soil conservation department at every district place. One can get information about how to reduce soil erosion at this place. 15. Social forestry : a. Planting of the trees on the borders of fields on the sides of roads and railway tracks and on the banks of rivers and streams is called social forestry. b. The government of India, in the year 1976, started social forestry projects for the benefit of the people. c. The project motivated the people to start planting of trees in all possible places. d. Tip project encourages small farmers and adivasis to plant trees. It provides financial assistance to them for this purpose. 16. Soil pollution : a. A disturbance in the natural balance of various constituents of soil is called soil pollution. b. Chemical fertilizers, pesticides, industria effluents, etc. Pollute the soil. c. Crops do not grow well on polluted soil. d. Soil pollution can be prevented by using organic fertilizers instead of chemical fertilizers. e. Overuse of fertilizers and pesticides should also be avoided for the prevention of the soil pollution. 17. Soil testing : a. Soil testing is done to find out the quality of the soil. b. Soil testing helps up to find out the colour, texture and the constituents of organic matter in the soil.

Short note on : Air Pollution

Due to industrialization, the waste chemical from the factories in the form of gases, liquids, solids are given out into the atmosphere, water and soil. When the collection of such chemical substances at any place increases beyond a certain level, the harmful effects can be seen . This is callee pollution. The contaminated water , dust, soot, chemicals, gases released in the atmosphere by the burning of carbon and sulphur, the harmful metals such as lead, aluminium, zinc, acids, bases cause pollution. The atmospheric pollution cause respiratory disorders, cancer of intestines, disorders of urinary bladder, high blood pressure, disorder of eyes etc . It leads to palpitations , breathlessness and psychological disorders. Pollution affects both animals and plants. To reduce pollution, efforts should be made to grow forests, treat chemical waste before letting out into the atmosphere, avoid the generation of harmful chemical substances, prevent the concentration of harmful chemicals at one place and industrial estates should be established away from cities.

Good Question : Why the copper wire used in an electromagnet is insulated ?

To make an electromagnet, insulated copper wire is wound around a rod of soft iron. The ends of the wire are connected to an electric cell through a key . As the wise is insulated there is on electrical contact between the wire and the rod. If the wire is bare i.e. Not insulated, there will be electrical contact between the wire and the rod and consequently between the adjacent turns of the wire . This will reduce the electrical resistance in the circuit significantly. He the key is closed under such condition, the wise will carry large current and become very got. In a short time practically all the electrical energy in the cell will be converted into heat. To avoid this the copper wise used in an electromagnet is insulated.

Simple Electric cell/ Voltas cell

In a simple electric cell, dilute sulphuric acid is taken in a glass trough and one plate of zinc (Zn) and another plate of copper (Cu) are dipped in it. The plates are separated by some distance. The Cu plate acts as the positive pole while the Zn plate acts as the negative pole. Using connecting wires of copper, a circuit consisting of the cell, an electric bulb and a key is formed. When the key is closed , the circuit is completed and an electric current flows through it from the positive sold to the negative sold through the connecting wires. The current is produced by the chemical reactions in the cell. The bulb glows due to the current. This cell is called Voltas cell.

Sodium peroxide

SODIUM PEROXIDE (Na2O2) Preparation : 1. By heating the metal in excess of air or oxygen at 300', which is free from moisture and CO2. 2Na + O2 (excess) --> Na2O2 2. Industrial method : It is a two stage reaction in the presence of excess air. 2Na + O2 --> Na2O Na2O + O2 --> Na2O2

Safety measures in using electricity.

1. Electric fuse : An electric fuse is a safety device used to save the electrical appliances 2. Wires carrying electricity should not be touched case footed. If we touch the wire bare footed, a large current may pass through our body. So we may receive severe shock. This shock may sometimes cause death. Therefore, while working with electricity we our year gloves made of insulated material and rubber soled shoes so that current may not flow through our body. 3. The insulation of the wire must be checked periodically. 4. Earthing : Many electrical appliances have a metallic body such as electric heater, toaster, oven, refrigerators etc. If by chance insulation of the wire melts, the live wire may touch the metallic body of the appliance. He we touch this body with case hands, we may receive a severe shock. To avoid such accidents, metal carings of all electrical appliances must be earthed. One end of a copper wire is connected to the metal case of the appliance and the other end is connected to the copper plate which is buried deep inside the earth. This system of connecting the metal casing of an electrical appliance with a copper plate buried deep inside the earth is called as earthing.