A series of reactions is performed in a sequence such that a visible change appears in a system. First, solid silver carbonate precipitate is produced. It is tan in color. This precipitate is dissolved in ammonia to give a colorless solution. Sodium chloride produces a white precipitate which dissolved in sodium thiosulfate to give a colorless solution.
Sodium iodide gives a yellow solid that turns black on the addition of sodium sulfide.
The sequence of reactions is arranged so that, for each succeeding step, silver is reacted with some constituent of the newly added reactant. The reactions are driven in that direction. Add 30 mL of 1 M Na 2 CO 3 and stir. Note evidence of reaction. Add 150 mL of 3.0 M NH 3 and stir.