DEPARTMENT OF CHEMISTRY
GOVERNMENT DEGREE
COLLEGE-PUTTUR
A
SYSTEMATIC ANALYSIS OF THE SALT MIXTURE
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EXPERIMENT
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OBSERVATION
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INFERENCE
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1)Primary tests:
A)
Physical state
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Crystal
(or) Amorphous
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----------
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B)
Colour
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blue
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May
be copper
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Green
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May
be nickel
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Pink
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May
be manganese
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pale
Green
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May
be ferrous
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colour
less
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Not
the above salts
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2)Solubility:
A
pinch of the salt is shaken with
i)Cold
water , hot water
ii)
Dil. HCl, hot Dil. HCl
iii)
Con. HCl, hot Con. HCl
iv)
Dil. HNO3, hot Dil. HNO3
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The
mixture is soluble in -----
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3)Action
of Heat:
A
pinch of salt is heated in a dry test
tube first slowly and then strongly
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Yellow
when hot and white when cold
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May
be Zink
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White
sublimation and a
gas with ammonia smell
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May
be Ammonium Salts
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Reddish brown gas
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May
be Nitrate
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Colorless
gas turning lime water milky
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May
be Carbonate
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Loss of crystallization
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None
of the above
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4)Flame
test
The
salt is made into a paste by mixing with 1 or 2 drops Conc. HCl. A small
amount of the paste is introduced into the flame using a charred splinter and
the colour of the flame is observed.
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Bluish
green (or) Blue
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May
be Copper
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Bright
green
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May
be Borate
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Apple
green
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May
be Barium
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Brick
Red
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May
be Calcium
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Bluish
white
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May
be lead
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Green
flashes
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May
be Zinc
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IDENTIFICATION OF ANAIONS ( DRY TESTS)
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1)Action
of dil. HCl:
A small amount of salt is treated with dil.
HCl.
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Brisk effervescence and the gas turns lime
water into milky
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May
be Carbonate
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A gas with rotten egg smell turning lead
acetate paper black
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May be Sulphide
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Gas
with burning sulphur smell – turns acidified K2Cr2O7
green
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May be Sulphite
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2)Action
of conc. H2SO4 :
A
little of the substance is heated with Conc. H2SO4.
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Colorless,
irritating gas giving dense white fumes with NH4OH
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Presence
of Chloride
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Immediate
reddish brown gas fumes turns yellow with NH4OH
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Presence
of Bromide
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Violet
vapors
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Presence
of Iodide
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Oily drops are formed. The test tube
acquires a greasy appearance. A colorless gas forming a white film on a wet
glass rod introduced is evolved.
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Presence of Fluoride
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3)Action
of conc. H2SO4+ Cu :
A
little of the salt is heated with a bit of copper turning & con.H2SO4
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Reddish
brown gas is formed. Solution becomes green/ blue.
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Presence
of Nitrate
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4)Action
of BaCl2:
A pinch of salt is treated with BaCl2 solution
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A
White precipitate is formed
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Presence
of Sulphate
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5)Oxalic
Acid test:
A
pinch of the salt is mixed with oxalic acid and rubbed with a drop of water
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Smell
of vinegar is observed
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Presence
of Acetate
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6)Ethyl
Borate test:
A
pinch of the salt is mixed with 3 drops of ethyl alcohol and 1 or 2 drops of
con. H2SO4. The solution is heated and the TT edge is brought near the Bunsen
flame
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Green
edge flame is observed
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Presence
of Borate
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7)Ammonium
Molybdate Test:
A
little of the salt is dissolved completely in conc. HNO3, cooled.
Then, added a few drops of ammonium
molybdate solution
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Yellow precipitate in cold or on slight
warming
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Presence
of Phosphate
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CONFIRMATION OF ANIONS (WET TESTS):
Preparation of Na2CO3
extract:
About 0.5 g of the salt is mixed with thrice
its amount of Na2CO3 and 10 ml of distilled water. The
solution is then boiled well for about 10 minutes and filtered. The filtrate
is known as “Na2CO3 extract”
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EXPERIMENT
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OBSERVATION
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INFERENCE
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1)Action
with AgNO3:
A
little of the extract is acidified with dil. HNO3 till
effervescence stops. Then AgNO3 is added
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(a)
A curdy white precipitate which is soluble in NH4OH
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Chloride
confirmed
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(b)
A pale yellow precipitate which is partly soluble in NH4OH
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Bromide
confirmed
Iodide
confirmed
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(c) A yellow precipitate insoluble in NH4OH
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2)Action
of BaCl2:
A
little of the extract is acidified with dil. HCl. Then BaCl2 is
added.
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A
white precipitate insoluble in conc. HCl
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Sulphate
confirmed.
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3)Brown
ring Test:
A little of the extract is acidified with
dil. H2SO4 and mixed with freshly prepared FeSO4 solution.
To this mixture, conc. H2SO4 is added along the sides
of the test tube without shaking.
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Brown
ring is formed when two solutions are in contact each other.
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Nitrate
confirmed.
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4)Action
with Neutral FeCl3:
A
little of the extract is acidified with dil. H2SO4 and
Neutral FeCl3 (ferric chloride) is added.
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Red
colour solution (or) Brown precipitate is formed.
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Acetate
confirmed.
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5)Action
with magnesium mixture:
A
little of the extract is acidified with dil. H2SO4 and
magnesia mixture is added.
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White
precipitate is formed.
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Phosphate
is confirmed.
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6)BF3
(boran trifloride) Test:
A
pinch of salt is mixed with equal bulk of CaF2, made a paste with 1
or 2 drops of con. H2SO4 and the paste is brought near
to the Bunsen flame.
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Green
edged flame is observed.
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Borate
is confirmed.
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IDENTIFICATION
OF AMMONIUM CATION :
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EXPERIMENT
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OBSERVATION
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INFERENCE
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Action
with NaOH:
The
salt is heated with few drop of NaOH.
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Ammonia
gas is given out with pungent smell and the gas gave dense white fumes with
con. HCl.
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May
be ammonium ion.
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Action
with Nesslers Reagent:
The
salt is dissolved in water and excess of Nessler’s reagent is added and then
few drop of NaOH.
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Brown
precipitate is formed.
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Ammonium
ion is confirmed.
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GENERAL GROUP SEPARATION TABLE
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6N HCl solution is added to the
original solution in slight excess, shaken well to complete the precipitation
and centrifuged.
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Residue:(white)
Group-I Cations present
AgCl-White
PbCl2-White
Hg2Cl2-white
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Centrifugate
(solution) is diluted, the acidity is maintained
and H2S gas is slowly passed and the mixture is centrifuged.
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Residue:
(colour)
Group-II
Cations present
HgS-Black
PdS-Black
Bi2S3-Brown
CuS-Black
CdS-Yellow
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Centrifugate
(solution) is boiled to expel H2S
completely. 3, 4 drops of con. HNO3
is added to oxidize any ferrous to ferric state. 0.2gr. NH4Cl and
NH4OH solution are added to get the smell of ammonia even after
shaking and then centrifuged.
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Residue:
(colour/white)
Group-III
Cations present
Fe(OH)3-brown
Al(OH)3-white
Cr(OH)3-Green blue
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Centrifugate
(solution) is treated with H2S in
excess and centrifuged.
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Residue
(colour/white)
Group-IV
Cations present
NiS-Black
MnS-Flesh
ZnS-Ash
/White
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Centrifugate (solution)
is boiled to expel the H2S gas and the volume of solution is reduced to 1/3rd
by boiling, then cooled
Dil.HCl+NH4OH+(NH4)2CO3 are added and centrifuged.
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Residue:
(white)
Group-V Cat ions present
BaCO3-white
SrCO3-white
CaCO3-white
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Centrifugate(solution)
is used to test Group-VI Cat ions.
K+
Mg+2
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GROUP-I CATIONS
SEPARITION TABLE
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The residue is washed with dil. HCl
and then boiled with few drops of water and centrifuged immediately
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Residue is treated
with few drops of NH4OH solution and centrifuged.
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Centrifugate is divided
into two parts
1st
part-
2 drops ammonium acetate and 1 drop potassium chromate are added to the
solution –yellow precipitate – lead ion(Pb+2) is present.
2nd
part-
few drops of KI is added, yellow precipitate is formed. When boiled-the
precipitate is dissolved and
reappeared as golden spangles on cooling –lead(Pb+2) is
conformed
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Residue is black in
colour- Mercury(Hg+) is present
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Centrifugate is treated with
few drops of HNO3 Solution , white precipitate reappeared-
Silver(Ag+) is Present
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GROUP-II CATIONS
SEPARITION TABLE
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The
2nd group residue is boiled with HNO3 and dil. H2SO4
then centrifuged.
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Residue:
the Residue is black in coilour mercury
is present
white
in colour Lead(Pb+2) is
present
5drops
saturated ammonium acetate and potassium cromate is added this residue -yellow precipitate is formed-
Lead(Pb+2)
is conformed
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Centrifugate: - the
solution is boiled after adding excess of NH4OH and
centrifuged.
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Residue:- white
precipitate- bismuth is present
This
residue is dissolved in dil KI solution and water is added drop by drop
–white turbidity is formed-
Bismath(Bi+3)
is conformed.
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Centrifugate:- the
solution is divided into two parts
1st
part:-
acetic acid and potassium Ferro cyanide solution are added-chocolate brown
precipitate is formed-cupper (Cu+2) is conformed
2nd
part:-
H2S gas passed through this solution –yellow precipitate formed-Cadmium
(Cd+2)is conformed
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GROUP-III CATIONS SEPARITION TABLE
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The 3rd group residue
boiled with 1 gm of Na2O2 (5 drops NaOH solution + 5
drops 30% H2O2)
and centrifuged
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Residue : the residue
may contain Fe+3 or Mn+2, the residue divided into two
parts
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Centrifugate:- the solution
may contain Cr or Al the
solution divided into two parts
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1st
part:-
the residue is dissolved in 3ml of HNO3, boiled with 50mg sodium
bismathate then cooled –pink colour solution appeared-
Manganese
(Mn+2) in conformed
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2nd
part:-
the residue is dissolved in 4drops HCl and few drops of potassium ferro
cyanide is added –blue colour solution is formed-
Ferric
ion (Fe+3) is conformed
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1st
part:-
3drops acetic acid and 4drops led acetate is added- yellow precipitate is
formed-
chromium
(Cr+3) is conformed
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2nd
part:-
HCl solution is added and made alkali with excess NH4OH –white
precipitate is formed-Alluminium(Al+3) is present
This
precipitate is dissolved in dil HCl , con NH3,0.5ml ammonium carbonate
and 4drops alluminan reagent are added and weifht for few minits-red
precipitate is formed-
Al+3
is conformed
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GROUP-IV CATIONS
SEPARITION TABLE
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The residue is dissolved in dil. HCl
and centrifuged
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Residue: Residue is
black in colour-Ni or Co is present
This
residue is taken in to porcelain dish con. HCl + con. HNO3 (3:1)
is added and slowly evaporated to dryness –yellow precipitate is observes-Nickel(Ni+2)
is present
Conformation: The residue
is made alkaline with NH4OH and few drops of dimethyl glyoxime are
added-Red colour precipitate appeared-
Ni+2
is conformed
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Centrifugate: the solution
is boiled to expel H2S gas completely; excess of NaOH solution is
added and centrifuged.
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Residue: the residue
brown in colour-Manganese is present
Conformation: the residue
is dissolved in con. HNO3 a pinch of sodium bismathate is added ,
boiled and diluted with water.-brown/pink solution is appeared-Manganese(Mn+2)
is conformed
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Centrifugate: H2S
gas passed through this solution –white precipitate appeared-Zinc(Zn+2)
is present
Conformation: this
precipitate is dissolved in con. HNO3 and then treated with cobalt
nitrate. A filter paper dipped in this solution is burnt it- green ash is
formed-
Zinc
is confirmed
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GROUP-V CATIONS SEPARITION TABLE
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The residue is dissolved in hot dilute acetic acid and add
K2CrO4 then centrifuged
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Residue: The residue
is yellow in colour it is barium
This
residue is used for flame test –apple green flame is observed –Barium
(Ba+2) is present
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Solution: To this
solution add 2 ml of saturated ammonium sulphate solution and boiled it then
centrifuged.
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Residue : The residue
is white in colour - Stransium (Sr+2) is present
This
residue is used for flame test -Red flame is observed –
Stransium
(Sr+2) is present
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Solution : to this
solution excess of ammonium oxalate is added and boiled in hot water bath-white
precipitate is formed - This residue is used for flame test –Brick Red flame
is observed –
Calcium(Ca+2)
is present
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ANALYSIS
OF GROUP-VI CATIONS
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The solution is divided into two parts
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Potassium
ion test: to
the 1st part of the solution saturated tartaric acid is added and
the sides are scratched with glass rod. White precipitate is formed – K+
is present
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Potassium
conformation test:
to the 2nd part picric acid is added, yellow precipitate is
formed.- K+ is
conformed
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Result:
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Anions
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Cations
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1.
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1.
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2.
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2.
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