1. Fe3+, Al3+, Cr3+, Ni2+, Co2+, Mn2+, Zn2+
3. GROUP CATIONS
Fe3+, Al3+, Cr3+, Ni2+, Co2+, Mn2+, Zn2+

2. These cations precipitate as sulfides and hydroxides when reacted with hydrogen sulfide (H2S) or thioacetamide solution in basic medium buffered with NH4OH – NH4Cl. These cations do not precipitate with the reagents used for precipitation of the group I and II.cations.
Group III cations are divided into two:
1) Iron Group (Group 3A): Fe3+, Al3+, Cr3+ (precipitates in the form of hydroxides).
2) Zinc Group (Group 3B): Ni2+, Co2+, Mn2+, Zn2+ (precipitates in the form of sulfides).

3. Systematic analysis of group III cations:
20 drops of sample containing Fe3+, Al3+, Cr3+, Ni2+, Co2+, Mn2+, Zn2+ taken into a tube from the sample.
Add 10 drops of 4 M ammonium chloride (NH4Cl) solution and 10 drops of 2 M ammonium hydroxide (NH4OH, %33) solution dropwise to the sample and check the basicity of the solution with a litmus paper.
Then add 20 drops of NH4OH solution and Fe3+, Al3+ and Cr3+ precipitate as their hydroxides.
Heat the solution for 5 min at water bath and add 20 drops of thioacetamide solution (11%, w/v) and observe precipitates of sulfides of Ni2+, Co2+, Zn2+ and Mn2+ (COMMON PRECIPITATE)
This precipitate contains Al(OH)3, Cr(OH)3, Fe(OH)3, NiS, CoS, MnS, and ZnS and it is washed several times with 0.1 M NH4Cl.
Add 20 drops of 6 M HCl onto the washed precipitate.
Centrifuge and separate the supernatant A and the precipitate A.

4. Precipitate A (CoS ve NiS):
Precipitate A is taken into cruicible, heated on bunsen burber till the solute part evaporates if exist, and add 20 drops of aqua regia (15 drops of 6 M HCl + 5 drops of 6 M HNO3) to dissolve the precipitate.
Add from NH4OH (%33) solution until it is basic (check with red litmus paper).
Divide the solution into two parts. To the first part, add 10 drops of 0.1 M potassium ferricyanide (K4[Fe(CN)6]) solution and the dark green color is followed, which is the precipitate of cobalt ferricyanide (Co2[Fe(CN)6]). This shows the presence of Co+2.
To the second part, add 2 drops of 6 M NaOH and 2 drops of dimethyl glyoxime (%1 in 96% alcohol), the rose color shows the presence of Ni+2.

5. Supernatant A (Fe3+, Al3+, Cr3+, Mn2+, Zn2+ ):
Add 20 drops of 6 M NaOH and 20 drops of 3% H2O2 (v/v) are added to the supernatant.
Centrifuge and separate supernatant B and the precipitate B.
Transfer precipitate B to a clean test tube, add 10 drops of HNO3 (37.5%) and pinches of spatula sodium bismuthate (NaBiO3) from the side of the tube. The color of violet proves the presence of Mn2+.
Add 0.1 M K4[Fe(CN)6] to the precipitate B, the prussian blue precipitate proves the presence of Fe3+.

6. Supernatant B (Zn2+, Al3+, Cr3+):
Add 20 drops of HNO3 and NH4OH to the solution until it is basic. Centrifuge and separate the supernatant C and the precipitate C
Precipitate C is white aluminum hydroxide (Al(OH)3).
The yellow color of the supernatant C, which contains Cr3+ and Zn2+, indicates the presence of Cr3+.
Add 20 drops of 2 M CH3COOH to the supernatant C to make the medium acidic. Add pinches of spatula of sodium acetate (NaCH3COO).
Heat the solution in a water bath for 20 min and add 2 drops of 0.5 M barium chloride (BaCl2) solution to the hot solution. The formed yellow precipitate (precipitate D) is barium chromate (BaCrO4).
Add 2 drops of thioacetamide solution (11% w/v) to the supernatant D and heat it up in the water bath with stirring for 5 minutes until the white precipitate is visible. The formation of dirty white zinc sulfide (ZnS) shows the presence of Zn2+.

8. Al(OH)3, Cr(OH)3, Fe(OH)3, NiS, CoS, MnS, ZnS
SUPERNATANT A: (Fe3+, Al3+, Cr3+, Mn2+, Zn2+ )
dark green color Co +2
Transfer to a clean test tube
10 drops of HNO3
pinches of spatula sodium bismuthate (NaBiO3) from the side of the tube
PRECIPITATE A: CoS, NiS
III. GROUP CATIONS
20 drops of sample
10 drops of 4 M NH4Cl
Dropwise 2 M NH4OH
check the basicity of the solution with a litmus paper.
20 drops of NH4OH eklenir.
Heat the solution for 5 min at water bath and add 20 drops of thioacetamide solution
COMMON PRECIPITATE
Al(OH)3, Cr(OH)3, Fe(OH)3, NiS, CoS, MnS, ZnS
Wash several times with 0.1 M NH4Cl
Add 20 drops of 6 M HCl
Centrifuge and separate the supernatant A and the precipitate A.
aken into cruicible, heated on bunsen burber till the solute part evaporates
20 drops of aqua regia (15 drops of 6 M HCl + 5 drops of 6 M HNO3) to dissolve the precipitate.
Add 2 M NH4OH check the basicity with red litmus paper.
2 drops of 6 M NaOH
2 drops of dimethyl glyoxime
Add 0.1 M (K4[Fe(CN)6])
SUPERNATANT C: Cr3+, Zn2+
Violet color,
Mn2+
white aluminum hydroxide (Al(OH)3)
2 drops of thioacetamide solution heat it up in the water bath with stirring for 5 minutes until the white precipitate is visible.
20 drops 2 M CH3COOH
pinches of spatula of sodium acetate (NaCH3COO)
Heat the solution in a water bath for 20 min
add 2 drops of 0.5 M barium chloride (BaCl2) solution to the hot solution.
20 drops of 6 M NaOH
20 drops of 3%
H2O2 Centrifuge and separate supernatant B and the precipitate B.
PRECIPITATE B Fe(OH)3, MnO2
20 drops of HNO3
add NH4OH until it is basic.
Centrifuge and separate the supernatant C and the precipitate C
SUPERNATANT B: Zn2+, Al3+, Cr3+
10 drops of 0,1 M (K4[Fe(CN)6])
rose color Ni +2
prussian blue precipitate Fe3+
PRECIPITATE C
PRECIPITATE D
Yellow precipitate barium chromate BaCrO4
SUPERNATANT D
dirty white precipitate
ZnS
Divide the sample into two

9. Al(OH)3, Cr(OH)3, Fe(OH)3, NiS, CoS, MnS, ZnS
SUPERNATANT A: (Fe3+, Al3+, Cr3+, Mn2+, Zn2+ )
dark green color Co +2
Transfer to a clean test tube
10 drops of HNO3
pinches of spatula sodium bismuthate (NaBiO3) from the side of the tube
PRECIPITATE A: CoS, NiS
III. GROUP CATIONS
20 drops of sample
10 drops of 4 M NH4Cl
Dropwise 2 M NH4OH
check the basicity of the solution with a litmus paper.
20 drops of NH4OH eklenir.
Heat the solution for 5 min at water bath and add 20 drops of thioacetamide solution
COMMON PRECIPITATE
Al(OH)3, Cr(OH)3, Fe(OH)3, NiS, CoS, MnS, ZnS
Wash several times with 0.1 M NH4Cl
Add 20 drops of 6 M HCl
Centrifuge and separate the supernatant A and the precipitate A.
aken into cruicible, heated on bunsen burber till the solute part evaporates
20 drops of aqua regia (15 drops of 6 M HCl + 5 drops of 6 M HNO3) to dissolve the precipitate.
Add 2 M NH4OH check the basicity with red litmus paper.
2 drops of 6 M NaOH
2 drops of dimethyl glyoxime
Add 0.1 M (K4[Fe(CN)6])
SUPERNATANT C: Cr3+, Zn2+
Violet color,
Mn2+
white aluminum hydroxide (Al(OH)3)
2 drops of thioacetamide solution heat it up in the water bath with stirring for 5 minutes until the white precipitate is visible.
20 drops 2 M CH3COOH
pinches of spatula of sodium acetate (NaCH3COO)
Heat the solution in a water bath for 20 min
add 2 drops of 0.5 M barium chloride (BaCl2) solution to the hot solution.
20 drops of 6 M NaOH
20 drops of 3%
H2O2 Centrifuge and separate supernatant B and the precipitate B.
PRECIPITATE B Fe(OH)3, MnO2
20 drops of HNO3
add NH4OH until it is basic.
Centrifuge and separate the supernatant C and the precipitate C
SUPERNATANT B: Zn2+, Al3+, Cr3+
10 drops of 0,1 M (K4[Fe(CN)6])
rose color Ni +2
prussian blue precipitate Fe3+
PRECIPITATE C
PRECIPITATE D
Yellow precipitate barium chromate BaCrO4
SUPERNATANT D
dirty white precipitate
ZnS
Divide the sample into two

10. When excess NH3 is added to the starting solution, red brown color indicates the presence of the Fe3+, and/or colorless and gelatinous precipitate indicates the presence of Al3+.