Section I
Anions
I- Carbonate group
Carbonate (CO3--) AND
Test
Bicarbonate (HCO3-)
Carbonate
CO3--
Bicarbonate
HCO3-
Effervescence due to
evolution of CO2 gas
Effervescence due to
evolution of CO2 gas
2- BaCl2 test
White ppt on cold
(the ppt is soluble in dil
HCl)
White ppt after boiling
(the ppt is soluble in dil
HCl)
3- MgSO4 test
White ppt on cold
White ppt after boiling
4- HgCl2 test
Reddish brown ppt
No Characteristic
Observation
1-dil. HCl
1
II- Sulphur group
Sulphide (S--), Thiosulfate (S2O3--) AND Sulphate (SO4--)
Test
1-dil HCl test
Sulphide
S--
Thiosulfate
S2O3--
Sulphate
SO4--
Rotten egg odor
due to evolution of
H2S gas
Burnt sulphur odor +
yellowish white
turbidity after
worming
No ppt from dil
solution, if conc
solution → white ppt
Soluble in dil HCl
No reaction
white ppt insoluble
in dil HCl
2- BaCl2 test
No ppt
3- FeCl3 test
(sample + few
drops of FeCl3)
Black ppt
Purple color quickly
vanishes
No reaction
4- lead acetate
test
Black ppt
White ppt soluble in
dil HCl
White ppt insoluble
in dil HCl
5- AgNO3 test
Black ppt
White ppt → brown White ppt from conc.
→ black
solution
(1 drop of the sample
+ excess AgNO3 )
6- iodine test
1 mL of iodine
solution + few
drops of the
sample
Decolorization of
the brown color of
I2 + turbidity
Decolorization of the
brown color of I2 +
clear solution
Special test for sulphide: sodium nitroprusside test
( sample + 10 % NaOH + few drops of sodium nitroprusside)
2
No reaction
purple color
Section III
III- Halide group
Test
1- AgNO3 test
2- lead acetate test
Chloride
Cl-
Iodide
I-
White cruddy
ppt
yellow cruddy
ppt
White ppt.
Yellow ppt.
Special tests for Iodide:
1- Chlorine water test:
( sample + dil H2SO4 + few drops of chlorine water → shake well → add
few drops of chloroform → shake well
violet color in the chloroform
layer
2- HgCl2 test:
HgCl2 + one drop of the sample → scarlet red ppt soluble in excess
sample solution.
3- CuSO4 test:
Sample + dil H2SO4 + copper sulphate → white ppt in brown solution.
3
Cyanogen group
Thiocyanate (SCN-), Ferrocyanide [Fe(CN)6]-4AND
Ferricyanide [Fe(CN)6]-3
test
Thiocyanate
SCN-
Ferrocyanide
[Fe(CN)6]-4
Ferricyanide
[Fe(CN)6]-3
1-AgNO3 test
White ppt
White ppt
Orange red ppt.
2- FeCl3 test
(FeCl3 + drop
by drop of
the sample)
Blood red color
Prussian blue ppt
Brown color
3- FeSO4 test
No reaction
White ppt. change
rapidly into blue ppt.
Dark blue ppt.
4- CuSO4 test
( 1 mL
sample +
drop by drop
of CuSO4)
Emerald green color
Chocolate brown ppt.
Green ppt.
5- Co(NO3)2
test
1 mL Co(NO3)2 + 0.5
gm solid Thiocyanate
sample → blue color
Grayish green ppt.
Red ppt.
4
Scheme for Anions
1- Action of dil HCl
On cold :
* effervescence → CO3-- or HCO3- (differentiation by HgCl2 test)
* rotten egg odor → it's S-On hot :
* burnt sulphur odor + yellowish white turbidity → it's S2O3-* If no characteristic observation → step (2)
2- Action of FeCl3:
1- blood red color → it's SCN2- dark blue ppt. → it's ferrocyanide
3- Black ppt→ it's S-4- purple color quickly vanishes → it's S2O3-5- reddish brown ppt. → it's CO3-- or HCO3* If no characteristic observation → step (3)
3- Action of BaCl2:
* white ppt insoluble in dil HCl → it's SO4-* If no characteristic observation → step (4)
5
4- Action of AgNO3:
1- white ppt. → it's Cl2- Yellowish white ppt. → it's I-
5- Action of HgCl2:
Scarlet red ppt. → it's I-
6
Cations
The cations are the positively charged part of the salt.
The cations are classified into 6 groups.
A group is separated from the others by adding a
reagent which precipitate the cations of one group and
not the others.
This reagent is called the "Group Reagent".
Group I
Group reagent: dil HCl
Group precipitate: The cations of group I are
precipitated as chlorides.
Lead (Pb2+)
Test
Observation
Group reagent: Dil. HCl
(1 ml Sample + dil. HCl (drop by drop
with strong shaking )
7
White ppt.
Confirmatory tests for Pb2+
1- Potassium chromate (K2CrO4) test
(1 ml sample + 1 ml acetic acid + 1 ml
K2CrO4)
Yellow ppt.
2- Potassium iodide (KI) test
Yellow ppt.
3- Dil. H2SO4 test
White ppt.
Group II
Group reagent: dil. HCl + Na2S
Group precipitate: The cations of group II are
precipitated as Sulfides.
Lead (Pb2+), Copper (Cu2+), Mercuric (Hg2+)
AND Cadmium (Cd2+)
Pb2+ Cu2+
Hg2+
Cd2+
Black
ppt.
Black
ppt.
Yellow
ppt.
Test
Group reagent: Dil. HCl + Na2S
(1 ml Sample + 1 ml dil. HCl + 1 ml
Na2S)
8
Black
ppt.
Confirmatory Tests for Pb2+
Test
Observation
1- Potassium chromate (K2CrO4) test
(1 ml sample + 1 ml acetic acid + 1 ml
K2CrO4)
Yellow ppt.
2- Potassium iodide (KI) test
Yellow ppt.
3- Dil. H2SO4 test
White ppt.
Confirmatory Tests for Cu2+
Test
Observation
Emerald green color
1- KSCN Test
(2 ml sample + drop by drop of the
reagent)
2- Potassium iodide (KI) test
(1 ml sample + 1 ml reagent)
White ppt. in brown solution
Dark blue color
3- Conc. NH4OH test
(1 ml sample + 1 ml reagent)
Confirmatory Tests for Hg2+
Test
Observation
3- Potassium iodide (KI) test
(1 ml KI + drop by drop of the sample)
Scarlet red ppt. soluble in excess
sample
9
Group III
Group reagent: NH4Cl + dil. NH4OH
Group precipitate: The cations of group III are
precipitated as hydroxides.
Fe3+ AND Cr3+
Fe3+
Cr3+
Reddish brown ppt.
Grayish green ppt.
Test
Group reagent
NH4Cl + dil. NH4OH
(Sample + 1 ml NH4Cl
+ dil. NH4OH then
heating)
Confirmatory Tests for Fe3+
Test
Observation
1- KSCN Test
(1 ml sample + 1 ml reagent)
Blood red color
2- potassium ferrocyanide test
(1 ml sample + 1 ml reagent)
Dark blue ppt.
10
Confirmatory Tests for Cr3+
2 ml of the sample + 2 ml 30% NaOH + 1 ml H2O2 → Boil →
Yellow Solution
Divide the yellow solution into 2 portions and
perform the following tests:
Test
Observation
1- Portion I + 1 ml acetic acid +
1 ml lead acetate
Yellow ppt.
2- Portion II + 1 ml acetic acid +
1 ml BaCl2
Yellow ppt.
11
Group IV
Group reagent: NH4Cl + dil. NH4OH + Na2S
Group precipitate: The cations of group III are
precipitated as sulfides.
Co2+ AND Ni2+
Co2+
Ni2+
Black ppt.
Black ppt.
Test
Group reagent
NH4Cl + dil. NH4OH +
Na2S
(Sample + NH4Cl + dil.
NH4OH + Na2S then
heat)
Confirmatory Tests for Co2+
Test
Observation
1- potassium ferricyanide test
Reddish brown ppt.
2- Vogel's test
(Put few crystals of KSCN on a
watch glass and add few drops of
Co2+ sample)
Blue solution
12
Confirmatory Test for Ni2+
Test
Observation
DMG test:
( 1 ml sample + 1 ml dil NH4OH +
drop by drop of DMG)
Rose red ppt.
13
Group (V)
Group reagent: NH4Cl + dil. NH4OH +NH4(CO3)2
Group precipitate: The cations of group (V) are
precipitated as carbonates.
Ca2+ and Ba+2
1- Test for Ca2+
Test
Observation
Group reagent
*Sample + NH4Cl + dil. NH4OH then
warm , add NH4(CO3)2 and warm again
White ppt
Confirmatory Tests for Ca2+
1-Sample + solid NH4Cl + pot.
Ferrocyanide then warm for few
minutes
Creamy white ppt.
2-sample + solid NH4Cl + dil. NH4OH
+ ammonium oxalate then warm
14
White ppt.
2- Test for Ba+2
Test
Observation
Group reagent
*Sample + NH4Cl + dil. NH4OH then
warm , add NH4(CO3)2 and warm again
White ppt
Confirmatory Tests for Ba+2
Yellow ppt
1- sample + glacial acetic acid +
potassium Chromate
2-Sample + solid NH4Cl + pot.
Ferrocyanide then warm for few
minutes
No Creamy white ppt.
3-sample + solid NH4Cl + dil. NH4OH
+ ammonium oxalate then warm
No White ppt.
15
Group (VI)
*
This group does't have a common reagent that can precipitate
all of its cations, so each cation will be tested individually.
Mg2+ AND NH4
1- Test for NH4+
Test
+
Observation
Solid Na2CO3 test
(put few amount of Na2CO3
powder on a watch glass then
add the sample solution and
triturate well)
Ammonia odor
Best Wishes
Staff Members of Analytical Chemistry Department
16
A nalysis of unknow n
Physical characters :
Color :… … … … … … ...
odor :… … … … … …
Chem ical analysis :
Test
observation
Result
Conclusion: the sam ple is… … … … … … … … … … …
17