Potassium chromate solution is added to aqueous solutions of metal nitrate. The yellow precipitate t β Qualitative and Quantitative Analysis Chemistry Question
Question
Potassium chromate solution is added to aqueous solutions of metal nitrate. The yellow precipitate thus obtained are insoluble in acetic acid. These are subjected to flame test, flame colour of individual ppt. is/are:
π‘ Solution & Explanation
Step 1: Treatment of the aqueous solution with dilute HCl yields a white precipitate. Lead(II) chloride (PbCl2) is uniquely soluble in hot water but insoluble in cold water. Step 2: Upon heating, PbCl2 dissolves back into solution. When H2S is passed through this hot acidic solution containing Pb2+ ions, it precipitates as highly insoluble black lead(II) sulfide (PbS). Step 3: This characteristic behavior (HCl precipitation, hot water solubility, and H2S black precipitate formation) uniquely identifies the lead(II) ion (Pb2+), matching option (d).