What is the observation of adding sodium hydroxide to copper 2 chloride?

When sodium hydroxide (NaOH) is added to copper(II) chloride (CuCl2), a blue precipitate of copper(II) hydroxide (Cu(OH)2) forms. This reaction occurs because the hydroxide ions from sodium hydroxide react with copper(II) ions in solution. The overall reaction can be represented as CuCl2 + 2 NaOH → Cu(OH)2 (s) + 2 NaCl. The formation of the blue precipitate indicates the presence of copper(II) ions in the solution.