Why Does Co2+ Have a Pink Color?

[asdf1]

why is Co2+ pink?

 

[Astronuc]

In what form is CO₂ pink?

It is a colorless gas, and in solid form, I have observed it to be white.

Confirm here - http://en.wikipedia.org/wiki/Carbon_dioxide#Chemical_and_physical_properties

If something appears pink, then perhaps it reflects a little more red than at other wavelengths.

 

[HallsofIvy]

It really is a pain to try to figure out what people really mean!

I suspect that this person is really talking about CoF₂, cobalt fluoride which is a pink compound.

Look at
http://www.webelements.com/webelements/compounds/text/Co/Co1F2-10026172.html

 

[asdf1]

sorry about that! you're right~
i mean cobalt ion...
thank you!

 

[siddharth]

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.

 

[Astronuc]

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

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

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).

 

[asdf1]

thank you very much! :)