[funboy]

An industrial plant that specializes in cleaning up waste liquids is confronted with a problem of seperating the metal ions foudn in a large vat of solution.  By analysis, the solution was found to contain varying quantities of silver, barium and iron(III) ions.  Suggest a procedure for separating the metal ions by precipitation.

I figure I want to find a metal that is more active than silver, barium and iron.  I have an activity series chart that shows silver and iron on the chart but no barium.  Am I not thinking about the question properly??

[Borek]

Wrong approach. Think about solubilties of different salts. And search forums, I believe the same question was asked before.

Edit: it was asked twice.

[funboy]

After reading the other posts, I looked up a table of solubilities in water chart

Im confused with the responses the other members gave to the origina question because the chart I have shows that barion, iron(III) and silver are nearly insoluble in phosphates.  If I wanted to remove all three without seperating them seperately couldnt I just add a phosphate to the vat??  In doing this am I not abiding to some rule with the above three elements and thats why this wasnt suggested??

Chris

[Borek]

If I wanted to remove all three without seperating them seperately couldnt I just add a phosphate to the vat??

Should work OK. Just a note: you will probably want to add phosphoric acid, not phosphate.

[stoneburner]

The problem does indeed ask about SEPARATING the metals - not getting them out all together.
What other common anions are there besides phosphate? What are the solubilities of these salts?
(and don't overlook OH- as a comon anion....) 

[AWK]

I think, for total precipitation of these cations the best is Na2HPO4 or you need to control the pH of solution.