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Copper and ammonia: royal blue

A precipitate that dissolves again in excess reagent — a complex ion.

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What you do

1. Set the amount to 1 mL and add aqueous ammonia once: a pale blue precipitate.
2. Keep adding ammonia, 1 mL at a time, until the precipitate dissolves.

Safety in a real lab

⚠ Ammonia solution has an irritating vapour: work in a fume cupboard.

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