What colour precipitate do copper (II) ions produce when reacted with sodium hydroxide solution?

Copper (II) ions react with sodium hydroxide to produce a characteristic blue precipitate known as copper (II) hydroxide. The reaction involves the formation of insoluble copper (II) hydroxide from the aqueous copper (II) ions and sodium hydroxide, which is a strong base. The resulting blue precipitate can be observed when the two solutions are mixed, indicating the presence of copper (II) ions in the solution.

Other colors are associated with different metal ions or compounds; for instance, green precipitates could indicate the formation of other metal hydroxides, while white and yellow precipitates are associated with different chemical reactions or metal ions like lead or silver. Understanding the distinct color of the copper (II) hydroxide precipitate is important in qualitative analysis and helps confirm the identity of copper (II) ions in solution.