CuCl2+NaOH

Here’s what happens when CuCl2 is treated with NaOH in aqueous solution: - With just enough NaOH: - Reaction: CuCl2(aq) + 2 NaOH(aq) → Cu(OH)2(s) + 2 NaCl(aq) - Observations: A blue precipitate of Cu(OH)2 forms. - With excess NaOH (copper(II) hydroxide dissolves): - Reaction: Cu(OH)2(s) + 2 OH−(aq) → [Cu(OH)4]2−(aq) - In salt form: Na2[Cu(OH)4](aq) - Observations: The blue precipitate dissolves to give a deep blue solution. - Net ionic view (in presence of excess NaOH): Cu2+ + 4 OH− → [Cu(OH)4]2− - Overall equation with excess NaOH: CuCl2(aq) + 4 NaOH(aq) → Na2[Cu(OH)4](aq) + 2 NaCl(aq) Notes: - Cu(OH)2 is amphoteric and dissolves in excess base to form the tetrahydroxocuprate(II) complex [Cu(OH)4]2−. - Color changes: CuCl2 solution is blue-green; Cu(OH)2 precipitate is blue; [Cu(OH)4]2− solution is deep blue.