Ammonium chloroplumbate

The preferred preparation method is to introduce chlorine into the solution while dissolving lead dioxide in cold concentrated HCl. This prevents decomposition of PbCL to PbCb and enhances the formation of chloroplumbic acid, H2PbCl6 in solution. Addition of ammonium chloride precipitates out yellow ammonium chloroplumbate, (NH4)2PbCl6, which is filtered out. The yellow precipitate, on treatment with cold concentrated sulfuric acid, forms lead tetrachloride, which separates out as a yellow oily liquid. The reactions are ... 

Suspend 5 grams of lead dioxide in 20 ml of ice-cold concentrated hydrochloric acid, cool in ice, and pass in chlorine slowly, shaking the solution occasionally until it is clear. This operation may take about two hours. A solid white residue remains at the bottom of the tube, but the supernatant liquid should be a clear yellow. Decant the solution, and into it stir 5 grams of solid ammonium chloride. Yellow crystals of ammonium chloroplumbate, (NH4)2PbCl6, separate immediately. Filter them quickly and wash them with a little ice water and then with ice-cold alcohol. Dry them on a watch glass at room temperature. The salt may be left exposed to the air at room temperature for a few hours without appreciable decomposition, but it should be transferred to a tightly closed bottle for storage. The yield is about 60 per cent. 

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