Cation 3 Flashcards
Group 3 cations
● Iron (Fe3+ ) Ion
● Cobalt (Co2+ ) Ion
● Nickel (Ni2+ ) Ion
● Zinc (Zn2+ ) Ion
● Manganese (Mn2+ ) Ion
● Aluminum (Al3+ ) Ion
● Chromium (Cr3+ ) Ion
The cations of Group III are precipitated in a solution containing
ammonia (NH 3)
ammonium chloride (NH4CI)
And ammonium sulfide (NH 4)2S.
group precipitate is a mixture of
sulfide and hydroxides
The high concentration of sulfide ion necessary for precipitation of Group III sulfides is obtained in an
ammoniacal solution.
This basic solution also produces the precipitation of chromium and aluminum as hydroxides in Group III.
ammoniacal solution.
These hydroxides form a soluble group when dissolved in excess KOH solution.
-> Chromium hydroxide
-> Zinc hydroxide
~> Aluminum hydroxide
These hydroxides precipitate to form an insoluble group
- Manganese hydroxide
- Iron hydroxide
- Nickel hydroxide
- Cobalt hydroxide
CENTRIFUGATE may contain
aluminum, chromium, and zinc ions.
Day 2: RESIDUE may contain
iron, cobalt, manganese, and nickel ions
confirms the presence of ALUMINUM ION.
red precipitate
confirms the presence of CHROMIUM ION.
Formation of a blue color which fades rapidly
confirms the presence of ZINC ION.
Formation of a white precipitate
Confirmatory reagent of Manganese
sodium bismuthate
confirms the presence of FERRIC ION
Appearance of deep red coloration
Reagents used to confirm presence of COBALT ION
solid NaF (Sodium fluoride)
10 drops of alcoholic NH4CNS
confirms the presence of COBALT ION.
Appearance of blue-green color at the junction of the 2 liquids
Confirmatory reagent of NICKEL ION
4 drops of dimethylglyoxime.
confirms the presence of NICKEL ION.
Formation of a red precipitate
Black
FeS
CoS
NiS
White
ZnS
Al(OH)3
Pink
MnS
Green
Cr(OH)3