Analysis of Group Iii Cations

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ANALYSIS OF GROUP III CATIONS

Precipitation of Group III Cations and Separation into Subgroups

Analysis of Subgroup A of Group III Cations

Analysis of Subgroup B of Group III Cations (PART 1)

Analysis of Subgroup B of Group III Cations (PART 2)

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Use decantate from group II cations

Precipitate

Decantate

Consider as Group IIIB.

Consider as Group IIIA.

Centrifuge and separate.

Add 10 drops of 1M HCl.

Wash with few drops of H2O.

Precipitate

Decantate

Centrifuge and separate.

Proceed to Group IV Analysis.

NO

YES

Does precipitate occur?

Add 1 ml of NH3 and heat in water bath for 5 mins.

Add 1 ml of 5% thioacetamide and heat in water bath for 5 mins.

Use Group IIIA precipitate.

Add 1 drop of
Dimethylglyoxime.

Discard.

Dilute to 1 ml and divide into 3.

Boil solution and add 6M NH3 until slightly basic to litmus.

Decantate

Centrifuge and separate.

Precipitate

Discard.

Add 1 drop of 16M HNO3 and heat in water bath for 5 mins.

Wash with 4 drops of 1M HCl.

Add 3 drops 12M HCl.

Precipitate

Decantate

Centrifuge and separate.

Let stand for 1 min.

Acidify with 6M HOAc and add several KNO2 crystals

Acidify with 1 M HCl and add several NH4CNS crystals.

Warm mixture.

Add equal volume of acetone or ethanol and agitate the mixture afterwards.

Formation of yellow precipitate indicates presence of Co3+.

Formation of bright reddish pink precipitate means presence of Ni2+.

Formation of blue colored solution shows presence of Co2+.

Use Group IIIB decantate.

Add 1 ml of 4M HNO3 and evaporate.

Dissolve residue in 1 ml water and place it in a test tube.

Add 4M NaOH until precipitate forms. Add another 10 drops of NaOH.

Add 6 drops of 3% H2O2 and heat in water bath for 5 mins.

Precipitate

Decantate

Centrifuge and separate.

Proceed to Analysis of Group IIIB (Part 2).

Wash with 10 drops of H2O and add 1 drop of 4M NaOH.

Decantate

Centrifuge and separate.

Precipitate

Formation of purple colored solution shows presence of Mn2+.

Formation of red colored solution indicates presence of Fe2+.

Add 1 drop of 0.2M KSCN

Add small amount of NaBIO3 and 2 drops of 4M HNO3.

Add 1 ml of 4M HNO3 and 2 drops of 1M NaNO2. Stir and heat in water bath

Decantate

Centrifuge and separate.

Precipitate

Boil in water bath.

Discard.

Dilute to 1 ml and divide into 3.

Add 2 drops of 0.2M K4Fe(CN)6.

Formation of Prussian blue precipitate means presence of Fe3+.

Use decantate from part 1.

Add 6M HOAc until acidic to litmus and add 2-3 drops excess.

Centrifuge and separate.

Decantate

Precipitate

Divide in two parts.

Add 6M HOAc until precipitate dissolves and add 2 drops of aluminon.

Add 5 drops of 5% thioacetamide then heat in water bath.

Add 1M HOAc until acidic and add 2 drops of 0.1M Pb(OAc)2.

Add 1M (NH4)2CO3 until basic.

Add 6M HCl until precipitate dissolves and heat.

Formation of yellow precipitate shows presence of Cr2+.

Formation of red lake indicates presence of Al3+.

Neutralize with 6M NH3, add 10 drops of 1M HCl and add 5 drops of K4Fe(CN)6.

Formation of gray-green precipitate means presence of Zn2+.
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