Question

Design a seperation scheme for the following cations: Al3+, Ba2+, Cu2+, Mn2+

Answer 1

Separation of Al3+ (Group III), Ba2+ (Group V), Cu2+ (Group II), Mn2+ (Group IV) metal cations

1) To the mixture add 2 M HCl, H2O2 and saturate with H2S. A black precipitate of CuS appears. Filter out the precipitate. Separate the filtrate for next step.

2) The filtrate from above is boiled to remove H2S. Add NH4Cl (solid) to it, heat and add dilute NH3 solution. A white precipitate of Al(OH)3 appears. Filter out the precipitate. Separate the filtrate for next step.

3) To the filtrate from above we saturate with H2S. A pink precipitate of MnS appears. Filter the precipitate out. The filtrate now only has Ba2+ ion.

4) To the filtrate from above we add (NH4)2CO3. A white precipitate of BaCO3 appears. Filter the precipitate.

So we have succesfully separated the four cations in solution.