Chem Note (英皇教育 A[1].Fung) HKCEE å¸&cedil

Chem Note - A Fung Tel 23050505 Preparation p.1 Chemical preparation method 1 To prepare better fuels which burnt with less air

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Unformatted text preview: . A. Fung Tel: 23050505 Preparation p.1 Chemical preparation method 1. To prepare better fuels, which burnt with less air pollutants ------ Cracking (. ) Cracking breaks down large hydrocarbon molecules into many small hydrocarbon molecules in the presence of heat and catalyst but no air. (e 0` pÅ á @ ¥` ) Catalyst. porous pot / stone gaseous alkane and alkene or aluminum oxide liquid hydrocarbon glass wool with heavy oil Heat ª -j ˜ µ water . Example. HHHHH HCCCCC HHHHH HHHHH HHHHH CCCCCH HCCCCC HHHHH HHHHH 2. To prepare ethanol by fermentation s²½(è :ª HHH CCCH HH HCC HHH ) Procedure. Put some cooked rice and yeast solution in a conical flask. Then stopper it. After a few days, ethanol is obtained. C6H12O6 (aq) glucose 2 CO2 + 2 CH3CH2OH H cooked rice and yeast solution . A. Fung Tel: 23050505 3. Preparation p.2 To prepare polystyrene from styrene ( ) Procedure. Pour some liquid styrene and kerosene (catalyst) into the experimental set-up of heating under reflux (. ). HH H CC C C H C6H5 n H H C6H5 n opening . water out . water in ¬Ø condenser . reaction mixture¬ Ø ª ½, boiling stones Ø :ª ½, ¬ and heat . 4. To prepare urea-methanal thermosetting plastic ,(ø :ª ½ ¬ ) Procedure. Dissolve white urea solid in colorless methanal liquid in a test tube, then adding few drops of concentrated sulphuric acid as catalyst. Observation. At this moment, heat and colorless vapour (water vapour) are evolved and white solid (urea-methanal) is formed. . A. Fung Tel: 23050505 Preparation p.3 5. To prepare chlorine bleach by electrolysis of brine ( r> • ½ ) Procedure. In the electrolysis of concentrated sodium chloride solution, chlorine gas is formed at positive electrode (anode) and hydrogen gas is formed at negative electrode (cathode). Afterwards, sodium hydroxide is left in the solution. Finally, reacting chlorine and NaOH solution can produce chlorine bleach. 2 NaOH + Cl2 NaOCl + NaCl + H2O 6. To prepare ester by esterification (. ) Procedure. Adding alkanol and alkanoic acid and few drops of concentrated sulphuric acid (catalyst) into the set-up of heating under reflux. Stop heating when there is a fruity smell. Then pour the product mixture into concentrated NaCl solution to salt out the ester. Finally, use filtration to get the solid ester. product mixture filter funnel and ester solid is formed filter paper on solution surface solid ester conc. NaCl solution Example. ethanol + butanoic acid water + ethyl butanoate (. O O CH3 CH2 O H + HO C CH2CH2CH3 ) H2O + CH3CH2 O C CH2CH2CH3 . A. Fung Tel: 23050505 7. Preparation p.4 To prepare soap by saponification ( x ) Procedure. Heat oil and sodium hydroxide solution until two layers of liquid become one. Then cool down it. Afterwards, pour the product mixture into concentrated NaCl solution. Finally, get the solid soap by filtration. oil or grease soap cool down Oil + NaOH soap Two layer of liquid Heating become one layer. for 30 mins Pour the product mixture into conc. NaCl solution O O C17H33 8. C O C3H7 + NaOH C17H33 C O Filtration + Na + C3H7 OH To prepare nitrogenous fertilizer ---------- large ammonia sulphate crystal Procedure. Adding same molarity of ammonia solution and sulphuric acid in volume ratio of 2. 1. Then heat the solution until it becomes saturated (. ). Let it cool down and place it in room for few days. Large crystal is then formed. Obtain it by filtration (. ). 2 NH3 + H2SO4 (NH4)2SO4 cool down Large crystal XXXXXXXX Saturated solution Heat Large crystal ...
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This note was uploaded on 09/02/2011 for the course CHINESE 12 taught by Professor Cn during the Spring '11 term at CNUAS.

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