Colors of Copper (Cu)
- Page ID
- 128801
Required Training |
Required PPE |
---|---|
UC Lab Safety Fundamentals |
Lab coat, safety glasses/goggles, nitrile gloves |
Equipment |
Chemicals |
Large crystalizing dish |
100 mL 0.1 M CuSO4 (24.8 g pentahydrate or 16.0 g anhydrous, with 2 mL 3 M H2SO4, QS to 1 L) |
Stir bar |
3 M NaOH |
Stirplate |
16 mL 6 M NH4OH |
|
16 mL 6 M HNO3 |
Procedure: (Dispensary - make enough solution to do three runs)
- Pour 100 mL 0.1 M CuSO4 into a deep crystalizing dish.
- Stir with a stir bar.
- Add just enough 3 M NaOH (~4 mL) to form an insoluble precipitate.
- Add excess 6 M NH4OH (~16 mL) to form a dark blue solution.
- Add 6 M HNO3 (~16 mL) to go back to a light blue solution.
Discussion:
This demonstration demonstrates metal ion complexes can have different solubility and colors. After addition of NaOH, Cu(OH)2 is formed and is insoluble. After addition of NH4OH, the dark blue solution contains [Cu(NH3)4]2+. Addition of HNO3 forms a new light blue solution, different from the starting sulfate, [Cu(H2O)4]2+.
Hazards:
These copper complexes are toxic; handle with care and see SDS for accidental release or contact.
SOP:
Corrosive – Ammonium Hydroxide, Nitric Acid, Sodium Hydroxide
Disposal (by Storeroom)
Return all materials to the storeroom. The storeroom will collect the solution and dispose of it in a copper (cation) waste bottle, submitted to EH&S