metal ions

• adding sodium hydroxide to a solution of calcium / magnesium / aluminum ions they all produce a white precipitate
• testing for aluminium: if we add excess sodium hydroxide, then the aluminium precipitate redissolves
• testing for calcium: flame tests
• testing for copper: copper || ions react with sodium hydroxide to form a blue precipitate of copper(||) hydroxide
• testing for iron: iron || ions react with sodium hydroxide to form a green precipitate of iron (||) hydroxide
• testing for iron: iron ||| ions react with sodium hydroxide to form a brown precipitate of iron (|||) hydroxide