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
Molisch Test
Sample + 2 drops of - napthal
Observation
Inference
Reddish brown ring at junction of Carbohydrate present
2 layers
Fehling’s Test
Sample + Fehling’s solution + Yellow or red precipitate
warm in water bath.
Benedict’s Test
Sample + Benedict’s solution + Red precipitate
warm in water bath.
Conc. H2SO4 Test
Sample + Conc. H2SO4
Charring with burnt sugar smell.
Carbohydrate present
Carbohydrate present
Carbohydrate present
Result : The given foodstuff contains carbohydrates.
Experiment 2
Aim : To detect the presence of fats / oils in the given foodstuff.
Experiment
Spot Test
Sample placed between folds of filter paper and
crushed.
Solubility Test
Sample + chloroform
Acrolein Test
Sample + potassium bisulphate + heating
Result : The given foodstuff contains fats or oil
Observation
Inference
Appearance of translucent spot
Fats or oils present
Sample dissolves
Fats or oils present
Irritating smell due to acrolein
formation
Fats or oils present
Experiment 3
Aim : To detect the presence of protein in the given foodstuff.
Experiment
xanthproteic Test
Sample + few ml of conc. HNO3
Shake and leave undisturbed.
Millon’s Test
Sample + few drops of mercuric nitrate+
1 drop dil. HCl + Boil , Cool + 1drop NaNO3
+ Heat mixture
Biuret Test
Sample + 10% NaOH + dil. CuSO4
Ninhydrin Test
Sample + 0.1% ninhydrin solution + boil for 1
minute
Result : The given foodstuff contains proteins.
Observation
Inference
Yellow or deep yellow colour
Proteins
present
Deep red colour
Proteins
present
Violet colour
Proteins
present
Blue colour on cooling
Proteins
present
Identification of Functional Groups In Given Organic Compounds
Experiment 1
Aim : To test for the presence of unsaturation in a given organic sample.
Experiment
Bromine Test
0.2g of sample dissolved in
carbon tetrachloride + 2 drops
2% bromine
Baeyer’s Test
Sample dissolved in acetone +
few drops of 2% alkaline
potassium permanganate.
Observation
Inference
Disappearance of orange red or
brown colour.
Presence of unsaturation
Decolourisation of pink colour.
Presence of unsaturation
Experiment 2
Aim : To test for the presence of alcoholic group in a given organic sample.
Experiment
Ester Test
Sample + few drops of acetic acid +
Conc. H2SO4
Warm in a water bath.
Sample + small piece of Na metal
Iodoform Test
Sample + NaOH solution + solid I2
+ warm
Observation
Inference
Pleasant smell
Ester present
Effervescence with evolution of
hydrogen gas.
Presence of alcoholic group
Yellow precipitate
Presence of alcohol with
methyl ketone group
Experiment 3
Aim : To test for the presence of phenolic group in organic sample
Experiment
Litmus Test
Sample + blue litmus
FeCl3 Test
Sample + small amount of FeCl3
Observation
Inference
Blue litmus turns red
Presence of phenolic
group
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
White precipitate
Presence of phenolic
group
Green or brown
precipitate
Presence of phenolic
group
.
Experiment 4
Aim : To test for the presence of aldehyde group in organic sample.
Experiment
2,4 – Dinitrophenyl hydrazine
Test
2,4 – DNP + sample
Schiff’s Test
Sample + Schiffs Reagent
Fehling’s Test
Sample + Fehling’s solution +
warm in water bath
Tollen’s Test
Sample + Tollen’s solution +
warm in water bath
Observation
Inference
Yellow orange precipitate
Presence of aldehyde
group
Pink colour
Presence of aldehyde
group
Yellow or red precipitate
Presence of aldehyde
group
Silver mirror on sides of test
tube
Presence of aldehyde
group
Experiment 5
Aim : To test for the presence of carboxylic acid group in organic sample.
Experiment
Litmus Test
Sample + blue litmus
Observation
Inference
Blue litmus turns
red
Presence of carboxylic
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
NH3. Cool and add neutral FeCl3
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
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
Initial
1.
2.
Final
Volume of
KMnO4 used (ml)
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
Initial
Volume of
KMnO4 used (ml)
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
 Nature of the salt
 Original solution
+
NaOH + heat
 Original solution
+
Nessler’s reagent
Observation
White crystalline, dissolves
in water.
Gas with pungent smell of ammonia
evolved.
Forms dense white fumes with HCl
Inference
Brown precipitate
NH4+
confirmed
Experiment
Preliminary Test



Salt + dil. H2SO4
Salt + conc. H2SO4
Bring a rod dipped in NH4OH
near mouth of test tube
Confirmatory Test
 Water extract + silver nitrate
solution
Observation
No characteristic change
Colourless gas with pungent
smell evolved
Dense white fumes are
formed.
Curdy white precipitate
soluble in excess of
NH4OH
the presence
NH4+ indicated
cation in the
sample.
Inference
Absence of
CO32-, S2-, SO32-, NO2indicated
Cl- indicated
Cl- confirmed
2. Aim: To analyse the presence of anion and cation in the given salt sample.
Observation
of anion and
given salt
Result: The given salt is NH4Cl
Experiment
To analyse
Inference
Preliminary Test

No characteristic change
Salt + dil. H2SO4
 Salt + conc. H2SO4 + heat
+ copper chips
Confirmatory Test
 Water extract + ferrous
sulphate + conc. H2SO4
along sides of test tube
Experiment
 Nature of the salt
 Original solution +
Reddish brown vapours
evolve which intensify with
copper chips
Reddish brown ring is formed
at junction of two layers
Absence of
CO32-, S2-, SO32-, NO2indicated
NO3- indicated
NO3- confirmed
Observation
White crystalline, dissolves
in water.
Inference
No characteristic change
Absence of NH4+ indicated
NaOH + heat
White precipitate forms
Pb2+ indicated
 Original solution +
Dilute HCl
 Boil white precipitate Precipitate dissolves. Divide
into 2 parts
with water
Yellow precipitate
Pb2+ confirmed
 1 part of solution +
potassium chromate
Yellow precipitate
Pb2+ confirmed
 1 part of solution +
potassium iodide
Result:
The
given salt
is
Pb(NO3)2
3. Aim: To analyse the presence of anion and cation in the given salt sample.
Experiment
Preliminary Test

Salt + dil. H2SO4
Observation
No characteristic change
Inference
Absence of
CO32-, S2-, SO32-, NO2indicated
No characteristic change
 Salt + conc. H2SO4
White precipitate insoluble
Absence of
Cl-, Br-, I-, NO3-, CH3COO-,
C2O4-
 Salt + BaCl2 solution
Confirmatory Test
 Water extract + lead
acetate
in dilute HCl.
Indicated
SO42- indicated
White precipitate is formed
SO42- confirmed
Result: The given salt is Al2 (SO4)3
4. Aim: To analyse the presence of anion and cation in the given salt sample.
Experiment
 Nature of the salt
 Original solution +
Observation
White crystalline, dissolves
in water.
Inference
No characteristic change
Absence of NH4+
NaOH + heat
 Original solution +Dilute HCl
 Original solution +
Dilute HCl + H2S gas
 Original solution + NH4Cl(s) +
NH4OH
indicated
No characteristic change
Absence of Group I
indicated
No characteristic change
Absence of Group II
indicated
Gelatinous white precipitate.
Dissolve in dilute HCl and
divide
Al3+ indicated
Into 2 parts
 Part 1 + NaOH
 Part 2 + blue litmus+ NH4OH
dropwise
White precipitate soluble in
excess
NaOH.
Blue Lake (Blue precipitate
floating in colourless solution)
Al3+ confirmed
Al3+ confirmed
Experiment
 Nature of the salt
 Original solution +
Observation
White crystalline, dissolves
in water.
Inference
No characteristic change
Absence of NH4+ indicated
No characteristic change
Absence of Group I
NaOH + heat
 Original solution +
Dilute HCl
 Original solution +
Dilute HCl + H2S gas
indicated
No characteristic change
Absence of Group II
indicated
 Original solution + NH4Cl(s) +
NH4OH
No characteristic change
Absence of Group III
indicated
 Original solution + NH4Cl(s)
+ NH4OH + H2S gas
 Part 1 + NaOH
Part 2 + K4[Fe(CN)6]
Experiment
Preliminary Test

Salt + dil. H2SO4
White precipitate
Dissolve precipitate in HCl.
Boil off H2S. Divide into 2
parts
White precipitate soluble in
excess NaOH.
White or bluish white
precipitate.
Observation
No characteristic change
Zn2+ indicated
Zn2+ confirmed
Zn2+ confirmed
Inference
Absence of
CO32-, S2-, SO32-, NO2indicated
No characteristic change
 Salt + conc. H2SO4
 Salt + BaCl2 solution
Confirmatory Test
 Water extract + lead
acetate
White precipitate insoluble
in dilute HCl.
White precipitate is formed
Absence of
Cl-, Br-, I-, NO3-, CH3COO-,
C2O4Indicated
SO42- indicated
SO42- confirmed
Experiment
 Nature of the salt
 Original solution +
Observation
White crystalline, dissolves
in water.
Inference
No characteristic change
Absence of NH4+ indicated
NaOH + heat
Absence of Group I
 Original solution +
Dilute HCl
 Original solution +
Dilute HCl + H2S gas
 Original solution + NH4Cl(s) +
NH4OH
No characteristic change
indicated
Absence of Group II
No characteristic change
indicated
Absence of Group III
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)
+ NH4OH + H2S gas
Group V indicated
 Original solution + NH4Cl(s)
White precipitate
Dissolve precipitate in acetic
acid and divide into 3 parts
Yellow precipitate
+ NH4OH + (NH4)2CO3
 Part 1 + potassium chromate
Experiment
Preliminary Test



indicated
No characteristic change
Observation
No characteristic change
Inference
Absence of
CO32-, S2-, SO32-, NO2indicated
Curdy white precipitate
soluble in excess of
NH4OH
Cl- confirmed
Salt + dil. H2SO4
Salt + conc. H2SO4
Bring a rod dipped in NH4OH
near mouth of test tube
Confirmatory Test
 Water extract + silver nitrate
solution
Ba2+ confirmed
Result: The given salt is BaCl2
6. Aim: To analyse the presence of anion and cation in the given salt sample.
Observation
Inference
No characteristic change
Absence of
CO32-, S2-, SO32-, NO2indicated
Experiment
Preliminary Test

Salt + dil. H2SO4
No characteristic change
 Salt + conc. H2SO4
Absence of
No characteristic change
 Salt + BaCl2 solution
 Salt + conc. HNO3 + heat
+ ammonium molybdate
Canary yellow precipitate
formed
Cl-, Br-, I-, NO3-, CH3COO-,
C2O4Indicated
Absence of SO42- indicated
PO43- confirmed
Result: The given salt is Mg3(PO4)2
Experiment
 Nature of the salt
 Original solution +
Observation
White crystalline, dissolves
in water.
Inference
No characteristic change
Absence of NH4+ indicated
NaOH + heat
Absence of Group I
 Original solution +
Dilute HCl
 Original solution +
Dilute HCl + H2S gas
No characteristic change
Absence of Group II
No characteristic change
 Original solution + NH4Cl(s) + NH4OH
indicated
Absence of Group III
No characteristic change
 Original solution + NH4Cl(s)
+ NH4OH + H2S gas
indicated
Absence of Group IV
No characteristic change
 Original solution + NH4Cl(s)
+ NH4OH + (NH4)2CO3
indicated
No characteristic change
indicated
Absence of Group V
indicated
 Original solution + NH4Cl(s)
+ NH4OH + (NH4)2HPO4
White precipitate on
scratching
Inner side of test tube
Mg2+ confirmed