To Prepare a Pure Sample of Iodoform. Chemicals : Acetone

Preparation of Iodoform

Aim : To prepare a pure sample of iodoform.

Chemicals : Acetone – 5 ml Iodine – 5 g NaOH – 5 % Methylated spirit

Theory : CH3COCH3 + 4I2 + 4NaOH → CHI3 + 3NaI + CH3COONa + 2H2O

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 NaNO2 in 10 – 15 ml of distilled water in a boiling tube and cool in ice bath.  Add cooled aq. solution of NaNO2 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.

Experiment Observation Inference 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 + Red precipitate Carbohydrate present warm in water bath.

Conc. H2SO4 Test Sample + Conc. H2SO4 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.

Experiment Observation Inference Spot Test Sample placed between folds of filter paper and Appearance of translucent spot Fats or oils present crushed.

Solubility Test Sample + chloroform Sample dissolves Fats or oils present Acrolein Test Sample + potassium bisulphate + heating Irritating smell due to acrolein Fats or oils present formation

Result : The given foodstuff contains fats or oil Experiment 3

Aim : To detect the presence of protein in the given foodstuff.

Experiment Observation Inference xanthproteic Test Sample + few ml of conc. HNO3 Yellow or deep yellow colour Proteins Shake and leave undisturbed. present

Millon’s Test Sample + few drops of mercuric nitrate+ Deep red colour Proteins 1 drop dil. HCl + Boil , Cool + 1drop NaNO3 present + Heat mixture Biuret Test Sample + 10% NaOH + dil. CuSO4 Violet colour Proteins present Ninhydrin Test Sample + 0.1% ninhydrin solution + boil for 1 Blue colour on cooling Proteins minute 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.

Experiment Observation Inference Bromine Test 0.2g of sample dissolved in Disappearance of orange red or Presence of unsaturation carbon tetrachloride + 2 drops brown colour. 2% bromine Baeyer’s Test Sample dissolved in acetone + Decolourisation of pink colour. Presence of unsaturation few drops of 2% alkaline potassium permanganate.

Experiment 2

Aim : To test for the presence of alcoholic group in a given organic sample.

Experiment Observation Inference Ester Test Sample + few drops of acetic acid + Pleasant smell Ester present Conc. H2SO4 Warm in a water bath. Sample + small piece of Na metal Effervescence with evolution of Presence of alcoholic group hydrogen gas. Iodoform Test Sample + NaOH solution + solid I2 Yellow precipitate Presence of alcohol with + warm methyl ketone group

Experiment 3

Aim : To test for the presence of phenolic group in organic sample

Experiment Observation Inference Litmus Test Sample + blue litmus Blue litmus turns red Presence of phenolic group FeCl3 Test Sample + small amount of FeCl3 Green or reddish violet Presence of phenolic precipitate group Bromine Water Test Sample dissolved in water + bromine White precipitate Presence of phenolic water group Cerric Ammonium Nitrate Test Sample + water + heat + cerric ammonium Green or brown Presence of phenolic nitrate solution precipitate group

Experiment 4

Aim : To test for the presence of aldehyde group in organic sample.

Experiment Observation Inference 2,4 – Dinitrophenyl hydrazine Test Yellow orange precipitate Presence of aldehyde 2,4 – DNP + sample group Schiff’s Test Sample + Schiffs Reagent Pink colour Presence of aldehyde group Fehling’s Test Sample + Fehling’s solution + Yellow or red precipitate Presence of aldehyde warm in water bath group Tollen’s Test Sample + Tollen’s solution + Silver mirror on sides of test Presence of aldehyde warm in water bath tube group

Experiment 5

Aim : To test for the presence of carboxylic acid group in organic sample.

Experiment Observation Inference Litmus Test Sample + blue litmus Blue litmus turns Presence of carboxylic red acid group Sodium hydrogen carbonate Test Sample + pinch of NaHCO3 CO2 gas is evolved Presence of carboxylic acid group NaOH Test Sample + NaOH solution Sample is soluble Presence of carboxylic acid group FeCl3 Test Sample + water + NH4OH . Boil to remove Red or Yellow Presence of carboxylic NH3. Cool and add neutral FeCl3 precipitate 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 K2SO4Al2(SO4)3·24(H2O). It is formed by adding equimolar mixture of hydrated aluminium sulphate and potassium sulphate crystals with minimum amount of sulphuric acid. K2SO4 + Al2(SO4)3·18(H2O) + 6 H2O → K2SO4Al2(SO4)3·24(H2O).

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 Fe2+ ions from the solution and acquires a positive charge which stabilizes the sol. FeCl3 + 3H2O → 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 KMnO4 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 KMnO4 + 3H2SO4 → K2SO4 + 2MnSO4 + 3H2O + 5[O] COOH 60°C | + [O] → 2CO2 + H2O ] x 5 COOH

2 KMnO4 + 3H2SO4 + 5(COOH)2 → K2SO4 + 2MnSO4 + 10CO2 + 10 H2O

Preparation of standard Solution : 250 ml of M/20 oxalic acid requires = 1.575 g of oxalic acid.

Indicator : KMnO4 is self indicator

End point : Colourless to pink

Procedure :  Rinse and fill burette with given KMnO4 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 H2SO4 to flask, shake and heat it to around 60°C  Note initial reading of burette ( upper meniscus)  Now add KMnO4 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 KMnO4 solution is ………..M

Record of Readings Molarity of oxalic acid = M/20 Volume of oxalic acid = 10 ml

S No. Burette Reading Volume of KMnO4 used (ml) Initial Final 1. 2.

Calculations KMnO4 = Oxalic acid a1 x V1 x M1 = a2 x V2 x M2

a2 x V2 x M2 M1 = a1 x V1 = 2 x 10 x M/20

5 X V1

= 1/(5V1) M = ………M

Titration of Potassium Permanganate vs Mohrs Salt

Aim : To determine the molarity and strength of KMnO4 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 KMnO4 + 3H2SO4 → K2SO4 + 2MnSO4 + 3H2O + 5[O] 2FeSO4.(NH4)2SO4.6H2O + [O] → Fe2(SO4)3 + 2(NH4)2SO4 + 13H2O] x 5

2 KMnO4 + 8H2SO4 + 10FeSO4.(NH4)2SO4.6H2O → K2SO4 + 2MnSO4 + 5Fe2(SO4)3 +10(NH4)2SO4 + 68 H2O

Preparation of standard Solution : 1000 ml of M/20 Mohr’s salt requires = 19.6 g of oxalic acid.

Indicator : KMnO4 is self indicator

End point : Colourless to pink

Procedure :  Rinse and fill burette with given KMnO4 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) H2SO4 to flask, shake.  Note initial reading of burette ( upper meniscus)  Now add KMnO4 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 KMnO4 solution is ………..M. (ii) The strength of KMnO4 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 KMnO4 used (ml) Initial Final

1. 2.

Calculations (i) KMnO4 = Mohr’s salt a1 x V1 x M1 = a2 x V2 x M2

a2 x V2 x M2 M1 = a1 x V1 = 2 x 20 x M/20

10 X V1

= 2/(10V1) M = ………M

(ii) Strength of KMnO4 solution = molarity x molecular mass = 2/(10V1) M x 158 = ……….g/l.

Salt Analysis 1. Aim: Experiment Observation Inference To analyse  Nature of the salt White crystalline, dissolves the presence in water. + of anion and  Original solution Gas with pungent smell of ammonia NH4 indicated + evolved. cation in the NaOH + heat Forms dense white fumes with HCl given salt

+ sample.  Original solution Brown precipitate NH4 + confirmed Nessler’s reagent

Experiment Observation Inference Preliminary Test No characteristic change Absence of 2- 2- 2- -  Salt + dil. H2SO4 CO3 , S , SO3 , NO2  Salt + conc. H2SO4 Colourless gas with pungent indicated smell evolved Dense white fumes are  Bring a rod dipped in NH OH 4 formed. Cl- indicated near mouth of test tube

Confirmatory Test  Water extract + silver nitrate Curdy white precipitate Cl- confirmed solution soluble in excess of NH4OH

Result: The given salt is NH4Cl

2. Aim: To analyse the presence of anion and cation in the given salt sample.

Experiment Observation Inference Preliminary Test Absence of 2- 2- 2- -  Salt + dil. H2SO4 No characteristic change CO3 , S , SO3 , NO2 indicated - Reddish brown vapours NO3 indicated  Salt + conc. H2SO4 + heat evolve which intensify with + copper chips copper chips

Confirmatory Test -  Water extract + ferrous Reddish brown ring is formed NO3 confirmed sulphate + conc. H2SO4 at junction of two layers along sides of test tube

Experiment Observation Inference  Nature of the salt White crystalline, dissolves in water.

 Original solution + + No characteristic change Absence of NH4 indicated NaOH + heat 2+  Original solution + White precipitate forms Pb indicated Result: Dilute HCl The  Boil white precipitate Precipitate dissolves. Divide given salt with water into 2 parts is 2+  1 part of solution + Yellow precipitate Pb confirmed Pb(NO3)2 potassium chromate  1 part of solution + Yellow precipitate Pb2+ confirmed potassium iodide

3. Aim: To analyse the presence of anion and cation in the given salt sample. Experiment Observation Inference Preliminary Test Absence of 2- 2- 2- -  Salt + dil. H2SO4 No characteristic change CO3 , S , SO3 , NO2 indicated

No characteristic change  Salt + conc. H2SO4 Absence of - - - - - Cl , Br , I , NO3 , CH3COO , - White precipitate insoluble C2O4  Salt + BaCl2 solution in dilute HCl. Indicated 2- SO4 indicated

Confirmatory Test 2-  Water extract + lead White precipitate is formed SO4 confirmed acetate

Result: The given salt is Al2 (SO4)3

4. Aim: To analyse the presence of anion and cation in the given salt sample.

Experiment Observation Inference  Nature of the salt White crystalline, dissolves in water.  Original solution + + No characteristic change Absence of NH4 NaOH + heat indicated

 Original solution +Dilute HCl No characteristic change Absence of Group I indicated  Original solution + No characteristic change Absence of Group II Dilute HCl + H2S gas indicated

 Original solution + NH4Cl(s) + NH4OH Gelatinous white precipitate. Al3+ indicated Dissolve in dilute HCl and divide Into 2 parts 3+  Part 1 + NaOH White precipitate soluble in Al confirmed excess NaOH. 3+  Part 2 + blue litmus+ NH4OH Blue Lake (Blue precipitate Al confirmed dropwise floating in colourless solution) Experiment Observation Inference  Nature of the salt White crystalline, dissolves in water.  Original solution + No characteristic change Absence of NH + indicated 4 NaOH + heat

 Original solution + No characteristic change Absence of Group I Dilute HCl indicated

 Original solution + No characteristic change Absence of Group II Dilute HCl + H2S gas indicated  Original solution + NH4Cl(s) + NH OH 4 No characteristic change Absence of Group III

indicated  Original solution + NH Cl(s) 4 + NH OH + H S gas 2+ 4 2 White precipitate Zn indicated Dissolve precipitate in HCl. Boil off H2S. Divide into 2 parts  Part 1 + NaOH White precipitate soluble in Zn2+ confirmed excess NaOH. 2+ Part 2 + K4[Fe(CN)6] White or bluish white Zn confirmed precipitate.

Experiment Observation Inference Preliminary Test Absence of 2- 2- 2- -  Salt + dil. H2SO4 No characteristic change CO3 , S , SO3 , NO2 indicated

Confirmatory Test 2-  Water extract + lead White precipitate is formed SO4 confirmed acetate

Experiment Observation Inference  Nature of the salt White crystalline, dissolves in water.  Original solution + + No characteristic change Absence of NH4 indicated NaOH + heat Absence of Group I  Original solution + No characteristic change indicated Dilute HCl Absence of Group II  Original solution + No characteristic change indicated Dilute HCl + H2S gas

 Original solution + NH4Cl(s) + Absence of Group III NH OH 4 No characteristic change indicated

Result: The given salt is ZnSO4 5. Aim: To analyse the presence of anion and cation in the given salt sample.

Absence of Group IV  Original solution + NH4Cl(s) indicated + NH4OH + H2S gas No characteristic change

Group V indicated  Original solution + NH4Cl(s) White precipitate

+ NH4OH + (NH4)2CO3 Dissolve precipitate in acetic acid and divide into 3 parts  Part 1 + potassium chromate Yellow precipitate Ba2+ confirmed

Experiment Observation Inference Preliminary Test No characteristic change Absence of 2- 2- 2- -  Salt + dil. H2SO4 CO3 , S , SO3 , NO2  Salt + conc. H2SO4 indicated

 Bring a rod dipped in NH4OH near mouth of test tube

Confirmatory Test  Water extract + silver nitrate Curdy white precipitate Cl- confirmed solution soluble in excess of NH4OH

Result: The given salt is BaCl2

6. Aim: To analyse the presence of anion and cation in the given salt sample.

Observation Inference Experiment

Preliminary Test Absence of 2- 2- 2- -  Salt + dil. H2SO4 No characteristic change CO3 , S , SO3 , NO2 indicated

No characteristic change  Salt + conc. H2SO4 Absence of - - - - - Cl , Br , I , NO3 , CH3COO , - C2O4 No characteristic change Indicated  Salt + BaCl2 solution 2- Canary yellow precipitate Absence of SO4 indicated  Salt + conc. HNO3 + heat formed 3- + ammonium molybdate PO4 confirmed

Result: The given salt is Mg3(PO4)2

 Original solution + NH4Cl(s) + NH4OH Absence of Group III No characteristic change indicated

 Original solution + NH4Cl(s) + NH OH + H S gas 4 2 Absence of Group IV indicated No characteristic change

 Original solution + NH4Cl(s) Absence of Group V + NH4OH + (NH4)2CO3 No characteristic change indicated

 Original solution + NH Cl(s) 4 + NH OH + (NH ) HPO 4 4 2 4 Mg2+ confirmed White precipitate on scratching Inner side of test tube