Precipitation and complexation of copper(II) with an ammonia solution
ammonia solution 3,5 %
copper(II) sulfate (or pentahydrate) Xn N R 22-36/38-50/53 S (2)-26-36/37/39-60-61
- Add into a test tube a small spatula-tipful copper(II) sulfate and dissolve with approx. 1 ml distilled water. A clear, slighty light blue solution develops.
- Add dropwise ammonia solution 3.5%. A voluminous, tough blue deposit is precipitated, which with further additions of ammonia is again dissolved, forming a clear, dark blue solution.
The diluted solution can be discharged into the drainage.
Copper(II) precipitates like many metallic cations in an alkaline milieu as a hydroxide. With a surplus of ammonia the soluble copper(II) tetraammine complex is formed - [Cu(NH3)4]2+.
diluted copper(II) sulfate solution
Precipitation of copper(II) hydroxide
copper(II) tetraammine solutions
derived from a school experiment