An unknown solution may contain any of the seven cations listed below. One stude

Question

An unknown solution may contain any of the seven cations listed below. One student preformed a series of experiments to determine what ions are in the solution. Based upon the experiments performed by the students, the results are as follows:

a) On addition of 6 M HCl, a white precipitate results. The white precipitate is then mixed with NH3 where it dissolves.

b) When acidic H2S is added to the unknown, a black precipitate results, and is dissolved in NH3 giving a deep blue color.

c) When ammonium carbonate, concentrated ammonia, and ammonium chloride are added to the unknown, a clear solution results.

Classify the following ions as present, absent, or undetermined. (input the whole word)

Silver-

Aluminum-

Barium-

Calcium-

Sodium-

Iron-

Copper-

Explanation / Answer

a)

from here, this must be either

Pb,Hg or Ag

if NH3 did not precipitated a product, then it cant be Hg

either Pb or Ag

b)

with H2S you will form PbS or Ag2S both are black

Silver- This is the snwer

Aluminum- NOT, since no Cl formation

Barium-NOT, since no Cl formation

Calcium-NOT, since no Cl formation

Sodium-NOT, since no Cl formation

Iron-NOT, since no Cl formation

Copper-NOT, since no Cl formation

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