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Colors of Copper (Cu)

  • Page ID
    128801
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    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)

    1. Pour 100 mL 0.1 M CuSO4 into a deep crystalizing dish.
    2. Stir with a stir bar.
    3. Add just enough 3 M NaOH (~4 mL) to form an insoluble precipitate.
    4. Add excess 6 M NH4OH (~16 mL) to form a dark blue solution.
    5. 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:clipboard_e2b48d4de6a94a0450be917720a7bdd1c.png

    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


    Colors of Copper (Cu) is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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