Preparation of Iodoform Aim : To prepare a pure sample of iodoform. Chemicals : Acetone 5 ml Iodine 5 g NaOH 5 % Methylated spirit Theory : CH 3 COCH 3 + 4I 2 + 4NaOH CHI 3 + 3NaI + CH 3 COONa + 2H 2 O Procedure: Dissolve 5 g of iodine in 5 ml acetone in a conical flask. Add 5 % sodium hydroxide solution slowly with shaking until the colour of iodine is discharged. Allow contents of flask to stand for 10 15 minutes. Filter the yellow precipitate of iodoform through Buchner funnel Wash the precipitate with cold water. Dry precipitate between filter paper and weigh it. Result : Yield of crystals 5 g Colour of crystals yellow Melting point 119 C. Precautions : Use freshly prepared sodium hydroxide. Add sodium hydroxide slowly and with constant stirring.
Preparation of 2- Naphthol Aniline or Aniline Yellow Aim : To prepare 2- Naphthol Aniline or Aniline Yellow dye. Chemicals : Aniline - 5ml Sodium nitrite 8g Dil. HCl (5N) 20 ml 2- Naphthol 8 ml NaOH - 3g Starch KI paper Theory : Procedure : Dissolve 5ml of aniline in 20 ml 0f dil.hcl in a boiling tube and cool in an ice bath. Dissolve 8 g NaNO 2 in 10 15 ml of distilled water in a boiling tube and cool in ice bath. Add cooled aq. solution of NaNO 2 slowly to cooled solution of aniline. Shake after each addition. Add few pieces of ice to reaction mixture. If diazotization is complete, the solution changes starch iodide paper to blue. Dissolve 3 g of NaOH in 10 ml of water in another boiling tube. Add 8 ml of 2- Naphthol to it slowly with shaking. Cool in an ice bath. Add solution of benzene diazonium chloride to the solution of 2- Naphthol in NaOH in small quantities with shaking. Orange dye is formed. Filter it in a buchner funnel. Wash the dye with water and dry it between folds of filter paper. Weigh it. Result : Yield of crystals 7 g Colour of crystals Orange Precautions Reaction mixture should be properly cooled. ph of coupling reaction should be between 9-10.
Detection of Carbohydrates, Proteins and Fats in the Given Foodstuff Experiment 1 Aim : To detect the presence of carbohydrate in the given foodstuff. Molisch Test Sample + 2 drops of - napthal Reddish brown ring at junction of Carbohydrate present 2 layers Fehling s Test Sample + Fehling s solution + Yellow or red precipitate Carbohydrate present warm in water bath. Benedict s Test Sample + Benedict s solution + warm in water bath. Red precipitate Carbohydrate present Conc. H 2 SO 4 Test Sample + Conc. H 2 SO 4 Charring with burnt sugar smell. Carbohydrate present Result : The given foodstuff contains carbohydrates. Experiment 2 Aim : To detect the presence of fats / oils in the given foodstuff. Spot Test Sample placed between folds of filter paper and crushed. Appearance of translucent spot Fats or oils present Solubility Test Sample + chloroform Sample dissolves Fats or oils present Acrolein Test Sample + potassium bisulphate + heating Irritating smell due to acrolein formation Fats or oils present Result : The given foodstuff contains fats or oil
Experiment 3 Aim : To detect the presence of protein in the given foodstuff. xanthproteic Test Sample + few ml of conc. HNO 3 Shake and leave undisturbed. Yellow or deep yellow colour Proteins present Millon s Test Sample + few drops of mercuric nitrate+ 1 drop dil. HCl + Boil, Cool + 1drop NaNO 3 + Heat mixture Deep red colour Proteins present Biuret Test Sample + 10% NaOH + dil. CuSO 4 Violet colour Proteins present Ninhydrin Test Sample + 0.1% ninhydrin solution + boil for 1 minute Blue colour on cooling Proteins present Result : The given foodstuff contains proteins.
Identification of Functional Groups In Given Organic Compounds Experiment 1 Aim : To test for the presence of unsaturation in a given organic sample. Bromine Test 0.2g of sample dissolved in Disappearance of orange red or Presence of unsaturation carbon tetrachloride + 2 drops 2% bromine brown colour. Baeyer s Test Sample dissolved in acetone + few drops of 2% alkaline potassium permanganate. Decolourisation of pink colour. Presence of unsaturation Experiment 2 Aim : To test for the presence of alcoholic group in a given organic sample. Ester Test Sample + few drops of acetic acid + Pleasant smell Ester present Conc. H 2 SO 4 Warm in a water bath. Sample + small piece of Na metal Effervescence with evolution of hydrogen gas. Presence of alcoholic group Iodoform Test Sample + NaOH solution + solid I 2 + warm Yellow precipitate Presence of alcohol with methyl ketone group Experiment 3 Aim : To test for the presence of phenolic group in organic sample Litmus Test Sample + blue litmus Blue litmus turns red Presence of phenolic group FeCl 3 Test Sample + small amount of FeCl 3 Green or reddish violet precipitate Presence of phenolic group
Bromine Water Test Sample dissolved in water + bromine water Cerric Ammonium Nitrate Test Sample + water + heat + cerric ammonium nitrate solution. Experiment 4 White precipitate Green or brown precipitate Presence of phenolic group Presence of phenolic group Aim : To test for the presence of aldehyde group in organic sample. 2,4 Dinitrophenyl hydrazine Test 2,4 DNP + sample Yellow orange precipitate Presence of aldehyde group Schiff s Test Sample + Schiffs Reagent Pink colour Presence of aldehyde group Fehling s Test Sample + Fehling s solution + warm in water bath Tollen s Test Sample + Tollen s solution + warm in water bath Yellow or red precipitate Silver mirror on sides of test tube Presence of aldehyde group Presence of aldehyde group Experiment 5 Aim : To test for the presence of carboxylic acid group in organic sample. Litmus Test Sample + blue litmus Blue litmus turns red Presence of carboxylic acid group Sodium hydrogen carbonate Test Sample + pinch of NaHCO 3 CO 2 gas is evolved Presence of carboxylic acid group NaOH Test Sample + NaOH solution Sample is soluble Presence of carboxylic acid group FeCl 3 Test Sample + water + NH 4 OH. Boil to remove NH 3. Cool and add neutral FeCl 3 Red or Yellow precipitate Presence of carboxylic acid group
Preparation of Crystals of Potash Alum Aim : To prepare crystals of potash alum Chemicals Required : 2.5 g of potassium sulphate, 10g of aluminium sulphate, 2-3 ml of conc. sulphuric acid. Theory : Potash alum is double salt of potassium sulphate and aluminium sulphate with composition K 2 SO 4 Al 2 (SO 4 ) 3 24(H 2 O). It is formed by adding equimolar mixture of hydrated aluminium sulphate and potassium sulphate crystals with minimum amount of sulphuric acid. K 2 SO 4 + Al 2 (SO 4 ) 3 18(H 2 O) + 6 H 2 O K 2 SO 4 Al 2 (SO 4 ) 3 24(H 2 O). Procedure : Take 2.5 g of potassium sulphate in a 250 ml beaker and dissolve it in a minimum amount of water by stirring with a glass rod. Heat if required. Take 10 g of aluminium sulphate in another beaker. Add 3-4 drops of dilute sulphuric acid to prevent hydrolysis. Then add 20 ml of water. Heat the beaker with constant stirring. Mix both solution in a china dish and concentrate mixture to crystallization point. Octahedral colourless crystals are obtained. Remove mother liquor carefully. Dry crystals between folds of filter paper and weigh them Result : Colour of Crystals : Colourless Shape of Crystals : Octahedral Weight of Crystals :.g Precautions : Add a few drops of dilute sulphuric acid while dissolving aluminium sulphate to prevent hydrolysis. Use ice cold water to wash potash alum as it is fairly soluble in water.
Preparation of Lyophobic Sol Aim : To prepare a sample of ferric hydroxide sol.. Chemicals Required : 0.2 M ferric chloride solution, distilled water. Theory : Hydrolysis of ferric chloride produces ferric hydroxide which undergoes agglomeration to give particles of colloidal dimension. These particles adsorb Fe 2+ ions from the solution and acquires a positive charge which stabilizes the sol. FeCl 3 + 3H 2 O Fe(OH) 3 + 3HCl (red sol) Procedure : Pour 100 ml of distilled water in a 250 ml beaker and place it on a wire gauze for heating. Add 0.2 M ferric chloride solution drop wise with the help of dropper to the boiling water. Continue heating till a deep red or a brown solution of ferric hydroxide is obtained. Allow contents of beaker to cool. Filter to remove precipitate of ferric hydroxide and collect filtrate in a beaker. The filtrate is ferric hydroxide sol. Precautions All glass ware should be free from impurities. Add ferric chloride solution very slowly drop by drop to boiling water. Use only distilled water. Result : A sample of lyopbobic colloid of ferric hydroxide has been prepared.
Preparation of Lyophilic Sol Aim : To prepare a sample of starch sol. Chemicals Required : 1g starch, distilled water. Theory : Starch forms lyophilic colloidal solution directly when mixed with hot water. Starch sol is stable and electrically neutral. Procedure : Pour 100 ml of distilled water in a 250 ml beaker and place it on a wire gauze for heating. Grind 1 g of soluble starch with a few ml of distilled water in a mortar and pestle to a fine paste. Pour the paste into boiling water with the help of a glass rod. Continue boiling for 2-3 minutes after addition of starch. Allow contents of beaker to cool and filter it with the help of filter paper. The filtrate is a starch solution. Precautions All glass ware should be free from impurities. Make a thin, fine paste of starch before adding to boiling water. Use only distilled water. Stir the contents continuously. Result : A sample of lyophilic colloid of starch has been prepared.
] Titration of Potassium Permanganate vs Oxalic Acid Aim : To determine the molarity of KMnO 4 by titrating it against standard solution of oxalic acid. Theory : Potassium permanganate oxidizes oxalic acid into carbon dioxide in acidic medium at a temperature around 60 C and itself gets reduced to colourless ions. 2 KMnO 4 + 3H 2 SO 4 K 2 SO 4 + 2MnSO 4 + 3H 2 O + 5[O] COOH 60 C + [O] 2CO 2 + H 2 O ] x 5 COOH 2 KMnO 4 + 3H 2 SO 4 + 5(COOH) 2 K 2 SO 4 + 2MnSO 4 + 10CO 2 + 10 H 2 O Preparation of standard Solution : 250 ml of M/20 oxalic acid requires = 1.575 g of oxalic acid. Indicator : KMnO 4 is self indicator End point : Colourless to pink Procedure : Rinse and fill burette with given KMnO 4 solution. Rinse the pipette with M/20 oxalic acid and pipette out 10.0 ml of it in a washed titration flask. Add half test tube of dilute H 2 SO 4 to flask, shake and heat it to around 60 C Note initial reading of burette ( upper meniscus) Now add KMnO 4 from burette till a permanent light pink colour is imparted to solution in titration flask. Note the final reading in the Burette. Repeat 4-5 times to get 3 concordant readings. Result : The molarity of KMnO 4 solution is..m Record of Readings Molarity of oxalic acid = M/20 Volume of oxalic acid = 10 ml S No. Burette Reading Volume of KMnO 4 used (ml) Initial Final 1. 2.
Calculations KMnO 4 = Oxalic acid a 1 x V 1 x M 1 = a 2 x V 2 x M 2 a 2 x V 2 x M 2 M 1 = a 1 x V 1 = 2 x 10 x M/20 5 X V 1 = 1/(5V 1 ) M = M
Titration of Potassium Permanganate vs Mohrs Salt Aim : To determine the molarity and strength of KMnO 4 by titrating it against standard solution of Mohrs Salt. Theory : Potassium permanganate oxidizes ferrous ammonium sulphate in acidic medium and itself gets reduced to colourless ions. 2 KMnO 4 + 3H 2 SO 4 K 2 SO 4 + 2MnSO 4 + 3H 2 O + 5[O] 2FeSO 4.(NH 4 ) 2 SO 4.6H 2 O + [O] Fe 2 (SO 4 ) 3 + 2(NH 4 ) 2 SO 4 + 13H 2 O] x 5 2 KMnO 4 + 8H 2 SO 4 + 10FeSO 4.(NH 4 ) 2 SO 4.6H 2 O K 2 SO 4 + 2MnSO 4 + 5Fe 2 (SO 4 ) 3 +10(NH 4 ) 2 SO 4 + 68 H 2 O Preparation of standard Solution : 1000 ml of M/20 Mohr s salt requires = 19.6 g of oxalic acid. Indicator : KMnO 4 is self indicator End point : Colourless to pink Procedure : Rinse and fill burette with given KMnO 4 solution. Rinse the pipette with M/20 Mohr s salt solution and pipette out 20.0 ml of it in a washed titration flask. Add one test tube of dilute (4N) H 2 SO 4 to flask, shake. Note initial reading of burette ( upper meniscus) Now add KMnO 4 from burette till a permanent light pink colour is imparted to solution in titration flask. Note the final reading in the Burette. Repeat 4-5 times to get 3 concordant readings. Result : (i) The molarity of KMnO 4 solution is..m. (ii) The strength of KMnO 4 solution is g/l. Record of Readings Molarity of Mohr s salt = M/20 Volume of Mohr s salt = 10 ml
S No. Burette Reading Volume of KMnO 4 used (ml) Initial Final 1. 2. Calculations (i) KMnO 4 = Mohr s salt a 1 x V 1 x M 1 = a 2 x V 2 x M 2 a 2 x V 2 x M 2 M 1 = a 1 x V 1 = 2 x 20 x M/20 10 X V 1 = 2/(10V 1 ) M = M (ii) Strength of KMnO 4 solution = molarity x molecular mass = 2/(10V 1 ) M x 158 =.g/l.
Salt Analysis Nature of the salt White crystalline, dissolves in water. Original solution + NaOH + heat Gas with pungent smell of ammonia evolved. Forms dense white fumes with HCl + NH 4 Original solution + Nessler s reagent Brown precipitate NH 4 + confirmed 1. Aim: To analyse the presence of anion and cation in the given salt sample. Preliminary Test Salt + dil. H 2 SO 4 Salt + conc. H 2 SO 4 Bring a rod dipped in NH 4 OH near mouth of test tube Colourless gas with pungent smell evolved Dense white fumes are formed. Absence of CO 3 2-, S 2-, SO 3 2-, NO 2 - Cl - Confirmatory Test Water extract + silver nitrate solution Curdy white precipitate soluble in excess of NH 4 OH Cl - confirmed Result: The given salt is NH 4 Cl 2. Aim: To analyse the presence of anion and cation in the given salt sample.
Preliminary Test Salt + dil. H 2 SO 4 Salt + conc. H 2 SO 4 + heat + copper chips Reddish brown vapours evolve which intensify with copper chips Absence of CO 3 2-, S 2-, SO 3 2-, NO 2 - NO 3 - Confirmatory Test Water extract + ferrous sulphate + conc. H 2 SO 4 along sides of test tube Reddish brown ring is formed at junction of two layers NO 3 - confirmed Nature of the salt White crystalline, dissolves in water. + Absence of NH 4 NaOH + heat White precipitate forms Pb 2+ Dilute HCl Boil white precipitate with water Precipitate dissolves. Divide into 2 parts 1 part of solution + Yellow precipitate Pb 2+ confirmed potassium chromate 1 part of solution + potassium iodide Yellow precipitate Pb 2+ confirmed Result: The given salt is Pb(NO 3 ) 2 3. Aim: To analyse the presence of anion and cation in the given salt sample. Preliminary Test Absence of Salt + dil. H 2 SO 4 CO 2-3, S 2-, SO 2- - 3, NO 2 Salt + conc. H 2 SO 4 Absence of Cl -, Br -, I -, NO - 3, CH 3 COO -, White precipitate insoluble - C 2 O 4
Salt + BaCl 2 solution in dilute HCl. Indicated SO 4 2- Confirmatory Test Water extract + lead acetate White precipitate is formed SO 4 2- confirmed Result: The given salt is Al 2 (SO 4 ) 3 4. Aim: To analyse the presence of anion and cation in the given salt sample. Nature of the salt White crystalline, dissolves in water. NaOH + heat + Absence of NH 4 Dilute HCl Dilute HCl + H 2 S gas NH 4 Cl(s) + NH 4 OH Part 1 + NaOH Part 2 + blue litmus+ NH 4 OH dropwise Gelatinous white precipitate. Dissolve in dilute HCl and divide Into 2 parts White precipitate soluble in excess NaOH. Blue Lake (Blue precipitate floating in colourless solution) Absence of Group I Absence of Group II Al 3+ Al 3+ confirmed Al 3+ confirmed
Nature of the salt White crystalline, dissolves in water. NaOH + heat + Absence of NH 4 Dilute HCl Dilute HCl + H 2 S gas NH 4 Cl(s) + NH 4 OH NH 4 Cl(s) + NH 4 OH + H 2 S gas Part 1 + NaOH Part 2 + K 4 [Fe(CN) 6 ] White precipitate Dissolve precipitate in HCl. Boil off H 2 S. Divide into 2 parts White precipitate soluble in excess NaOH. White or bluish white precipitate. Absence of Group I Absence of Group II Absence of Group III Zn 2+ Zn 2+ confirmed Zn 2+ confirmed Preliminary Test Absence of Salt + dil. H 2 SO 4 CO 2-3, S 2-, SO 2- - 3, NO 2 Salt + conc. H 2 SO 4 Absence of Cl -, Br -, I -, NO - 3, CH 3 COO -, White precipitate insoluble - C 2 O 4 Salt + BaCl 2 solution in dilute HCl. Indicated SO 2-4 Confirmatory Test Water extract + lead acetate White precipitate is formed SO 4 2- confirmed
Nature of the salt White crystalline, dissolves in water. NaOH + heat + Absence of NH 4 Dilute HCl Dilute HCl + H 2 S gas NH 4 Cl(s) + NH 4 OH Absence of Group I Absence of Group II Absence of Group III Result: The given salt is ZnSO 4 5. Aim: To analyse the presence of anion and cation in the given salt sample.
NH 4 Cl(s) + NH 4 OH + H 2 S gas Absence of Group IV NH 4 Cl(s) + NH 4 OH + (NH 4 ) 2 CO 3 White precipitate Dissolve precipitate in acetic Group V acid and divide into 3 parts Part 1 + potassium chromate Yellow precipitate Ba 2+ confirmed Preliminary Test Absence of Salt + dil. H 2 SO 4 CO 2-3, S 2-, SO 2- - 3, NO 2 Salt + conc. H 2 SO 4 Bring a rod dipped in NH 4 OH near mouth of test tube Confirmatory Test Water extract + silver nitrate solution Curdy white precipitate soluble in excess of NH 4 OH Cl - confirmed Result: The given salt is BaCl 2 6. Aim: To analyse the presence of anion and cation in the given salt sample. Experiment Observation Inference Preliminary Test Salt + dil. H 2 SO 4 Salt + conc. H 2 SO 4 Absence of CO 3 2-, S 2-, SO 3 2-, NO 2 - Absence of
Salt + BaCl 2 solution Salt + conc. HNO 3 + heat + ammonium molybdate Canary yellow precipitate formed Cl -, Br -, I -, NO 3 -, CH 3 COO -, C 2 O 4 - Indicated Absence of SO 4 2- PO 4 3- confirmed Result: The given salt is Mg 3 (PO 4 ) 2 Nature of the salt White crystalline, dissolves in water. NaOH + heat + Absence of NH 4 Dilute HCl Dilute HCl + H 2 S gas NH 4 Cl(s) + NH 4 OH NH 4 Cl(s) + NH 4 OH + H 2 S gas NH 4 Cl(s) + NH 4 OH + (NH 4 ) 2 CO 3 NH 4 Cl(s) + NH 4 OH + (NH 4 ) 2 HPO 4 White precipitate on scratching Inner side of test tube Absence of Group I Absence of Group II Absence of Group III Absence of Group IV Absence of Group V Mg 2+ confirmed