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Methods of Preparation (i) Laboratory method : By heating anhydrous calcium acetate in dry. (£H3COO)2Ca—* ch3coch3 + CaC03 Calcium acetate Acetone Experiment : Anhydrous calcium acetate is taken in a retort fitted with a condenser and a receiver. Retort is heated carefully when acetone distils over. The distillate is treated with a saturated solution of NaHS03 when acetone bisulphite compound separates out. It is filtered, dried and distilled with Na2C03 solution. The distillate obtained at 55°—66°C is dried over anhydrous CaCl2 and redistilled to obtain pure acetone (b.p. 56°C). Manufacture It is obtained on a large scale by the following methods. (i) From Pyroligneous Acid Pyroligneous acid is obtained by the destructive distillation of woods (see manufacture of methyl alcohol). It contains methyl alcohol, acetic acid and acetone (0-5%). Acetic acid is removed by passing the vapours through hot milk of lime. Methyl alcohol and acetone are separated by fractional distillation at 65°C and 56°C, respectively. Acetone, so obtained, is impure. It is purified by treatment with a saturated solution of NaHS03 as given in the laboratory method. (ii) From Acetic Acid By passing vapours over MnO at 300°-400°C. 2CH,COOH-M"° > CH,COCH, + CO, + H,0 300°—400°c l l (iii) From Isopropyl Alcohol ' Isopropyl alcohol is obtained from propylene formed during the cracking of petroleum. The vapours of alcohol are passed over copper at 300°C. CH, CH, \CHOH-^ \C = 0 + H2 ch3/ Cu CH3^ (iv) From Ethyl Alcohol By passing ethyl alcohol vapours mixed with steam over zinc chromite (catalyst) at 500°C. 2C2H5OH + H20 ZmC5C0h0rocm'te^ CH3COCH3 + C02 + 4H2 (v) From Acetylene By passing a mixture of acetylene and steam over heated pure ZnO as catalyst. 2C2H2 + 3H20 CH3COCH3 + C02 + 2H2 Properties Physical Acetone is a colourless, pleasant smelling liquid. It is miscible with water, alcohol etc. Its b.p. is 56°C. Chemical Please see 'General reactions of aldehydes and ketones' Uses (i) Acetone is widely used as a solvent, e.g., in the manufacture of cordite, collodion, artifical silk, varnishes, etc. (ii) It is used in storing and transportation of acetylene. (iii) It is used in synthesis of many organic compounds, e.g., chloroform, iodoform, chloretone, sulphonal, etc. (iv) It is used in the manufacture of mesitylene. Tests (i) Iodoform test : Acetone on heating with iodine and sodium hydroxide or ammonium hydroxide gives yellow crystals of iodoform having characteristic odour. (ii) Legal's test : Mixing of a freshly prepared solution of sodium nitroprusside to acetone and sodium hydroxide solution, gives a deep red colour which turns yellow on standing. Air is an essential thing for human survival. Without this, there is no survival of living beings in earth. It is composition of variety of gases. It consists of life sustaining substances like nitrogen, oxygen, carbon dioxide and small amounts of other elements like argon and neon. Atmospheric air also contains helium, ozone and hydrogen. Main constituents of air The main constituents of air is Nitrogen – 78 % Oxygen – 20% Noble gases – 1% Water vapor -0.03% Carbon dioxide- 0.97% Nitrogen: Nitrogen is the one of the main constituent present in air. The significance of nitrogen is respiration and combustion; it is very much important t in plants to produce proteins. Oxygen: Oxygen is the one of the main constituent present in air with 20 %. The significance of oxygen is respiration and combustion. Noble gases: Noble gases are the constituent only 1 % in air. The significance of noble gas is based upon the constituent of noble gas, in ballons helium is used, where neon in electronic advertisement signs, Radon is very useful for radiotherapy and cancer treatment. Learn more on abouthow to solve equations with fractions and its Examples. Between, if you have problem on these topics Herbicide Definition, please browse expert math related websites for more help.Please share your comment
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