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Homework Help: Why is Co2+ pink?

  1. Dec 13, 2005 #1
    why is Co2+ pink?
     
  2. jcsd
  3. Dec 13, 2005 #2

    Astronuc

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  4. Dec 13, 2005 #3

    HallsofIvy

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  5. Dec 13, 2005 #4
    sorry about that!!! you're right~
    i mean cobalt ion...
    thank you!!!
     
  6. Dec 13, 2005 #5

    siddharth

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    Adding to what HallsofIvy said, the colors of coordination compunds arises from the splitting of the d-orbitals as explained by the Crystal Field theory.
    If you want more information, you can look up any good inorganic chemistry book like Concise Inorganic chemistry by J.D Lee. I found that coordination compounds are explained well in it.

    EDIT: I assumed that you meant Cobalt 2+ complexes.
     
    Last edited: Dec 13, 2005
  7. Dec 13, 2005 #6

    Astronuc

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    Oops, sorry about that - my fault. The 2+ should have caught my attention.

    IIRC, in general the Co2+ is pink, or faintly red. On the other hand, chemweb has CoCl2 as being blue.

    A lot may depend on the ligands surrounding Co, since it forms complex ions.

    http://www.chemguide.co.uk/inorganic/transition/cobalt.html

    http://www.chemguide.co.uk/inorganic/complexions/ligandexch.html

    http://genchem.chem.wisc.edu/demonstrations/Gen_Chem_Pages/13equilpage/chloro_complexes_of_cobalt.htm [Broken]

    http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch12/complex.html [Broken]

    The color depends on the lightwave wavelengths transmitted or reflected. Something red would generally absorb blue light (or light at the blue end of the visible spectrum) and reflect or transmit red light (or light at the red end).
     
    Last edited by a moderator: May 2, 2017
  8. Dec 18, 2005 #7
    thank you very much!!! :)
     
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