A solution may contain Ag + , Pb 2+ , Al 3+ , Fe 3+ and Mn 2+ ions. Upon additio

Question

A solution may contain Ag+, Pb2+, Al3+, Fe3+ and Mn2+ ions. Upon addition of 6M HCl, a white precipitate formed (solid A). The solution, which contained the group II ions, was seperated from solid A which in a later step was placed in a hot water bath. The solution was decanted from the soluble chloride. The silver chloride formed a souble complex ion with the addition of aqueous ammonia.

The group II ion solution was made slightly basic to yield a precipitate (solid B). Solid B dissolbed upon treatment with nitric acid to form solution C that was then divided between two test tubes. Solution C turned a reddish-purple in the presence of NaBiO3 while the addition of KSCN afforded a dark red color in the other test tube. Which ion(s) are present, which are absent, or which may remain undeteremined? Indicate if any test(s) are needed to verify the presence of the undetermined ion.

Present:

Absent:

Yet to be determined:

Explanation / Answer

>The formation of white precipitates on addition of 6 M HCl indicates the presence of group I cations, i.e, Ag+ or Pb+2 (not confirmed which one of these).

>In solution C, the reddish brown color was obtained on addition of NaBiO3 due to the presence of Mn+2. This on addition of KSCN turned dark red in color.

Present : Mn+2, Ag+ or Pb+2

Absent : Al+3

Undetermined : Fe+3

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