Testing for a single cation in solution

The scheme follows the classification of cations into groups, as described in Section 3.1. 

Group I cations to the solution add an excess of dilute HCl. If there is no change, follow step 2. A white precipitate may contain Pb, Hg or Ag . Filter, wash and add NH3 solution. If the precipitate 

Group IIA cations to the acidified solution add H2S in excess. If there is no change, follow step 4. A precipitate may result if Pb , Hg, Cu , 

Sn or Sn were originally present. Filter the precipitate, wash with dilute HCl, and add an excess of (NH4)2S c. If the precipitate dissolves, follow step 3. If the remaining precipitate is 

Otherwise take a fresh sample and add dilute H2SO4. If the precipitate is 

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