Colours of Copper Cations (Cu+, Cu2+), Compounds, Coordination Complexes

There are two different copper cations as Cu+ and Cu2+. Colours of Cu+ and Cu2+ compounds are different and may be changed when they dissolve in water. Also Cu+ and Cu2+ cations form coordination complex compounds and they have different colours too. In this tutorial, we will discuss these stuff in detail.



  • Colours of cuprous / copper(I) ion (Cu+) compounds in solid state
  • Colours of cuprous ion (Cu+) compounds and coordination complexes in water
  • Colours of cupric ion / copper(II) ion (Cu2+) compounds in solid state
  • Colours of cupric ion (Cu2+) compounds and coordination complexes in water


Colours of cuprous / copper(I) ion (Cu+) compounds in solid state

Name of Cuprous / Copper(I) compound Chemical Formula Colour
Copper(I) chloride / Cuprous chloride CuCl White
Copper(I) bromide / Cuprous bromide CuBr White
Copper(I) iodide / Cuprous iodide CuI White
Copper(I) cyanide CuCN White to beige

Colours of cuprous ion (Cu+) compounds and coordination complexes in water

Above mentioned CuCl, CuBr, CuI and CuCN are insoluble in water and deposited as precipitates. Therefore, aqueous solutions are not found for those compounds.



Colours of cupric ion / copper(II) ion (Cu2+) compounds in solid state

Name of Cupric / Copper(II) compound Chemical Formula Colour
Copper(II) sulfate / Cupric sulfate CuSO4 White (when dehydrated) or
Copper(II) carbonate / Cupric carbonate CuCO3 Green
Copper(II) chloride / Cupric chloride CuCl2 yellowish - brown powder (in anhydrous form) / green crystalline solid (in dihydrate form)
Copper(II) bromide / Cupric bromide CuBr2 Black
Copper(II) oxide / Cupric oxide CuO Black to brownish-black
Copper(II) nitrate / Cupric nitrate Cu(NO3)2 Blue
Copper(II) sulfide / Cupric sulfide CuS Black

Colours of cupric ion (Cu2+) compounds and coordination complexes in water

Copper +2 cation can form coordination complexes with some ligands and anions. Those coordination complexes show various colours in aqueous medium. As Cu2+'s coordination complexes, some of Cu2+ compounds are soluble in water and some of them form precipitates in water.

Coordination complexes of Cu2+ cation

Name of Coordination complex of Cu2+ cation Chemical Formula Colour
hexaaquacopper(II) ion [Cu(H2O)6]2+ Blue
tetraamminediaquacopper(II) ion [Cu(NH3)4(H2O)2]2+ Blue
tetrachlorocuprate(II) ion [CuCl4(]2- olive-green or yellow


Colours of soluble compounds of Cu2+ cation

In this table, you can find the colours of aqueous solution which contains soluble compounds of Cu2+ cation.

Name of Cu2+ compound Chemical Formula Colour
Copper(II) sulfate / cupric sulfate (CuSO4) CuSO4 Blue
Copper(II) chloride / Cupric chloride CuCl2 blue - green
Copper(II) bromide / Cupric bromide CuBr2 Green
Copper(II) nitrate / Cupric nitrate Cu(NO3)2 Blue


How to produce coordination complexes of Cu2+ ion?

hexaaquacopper(II) ion ( [Cu(H2O)6]2+ )

Metallic copper reacts with following oxidizing acids. With each of following acid, copper oxidized Cu2+ cation. Then, you can see blue colour of aqueous Cu2+ solution.

  • Dilute nitric acid
  • Concentrated nitric acid
  • Concentrated sulfuric acid

3Cu(s) + 8HNO3(aq) + 18H2O(l) → 3[Cu(H2O)6](NO3)2(aq) + 2NO(g) + 4H2O(l)

HCl acid is not an oxidizing acid. Therefore, HCl cannot oxidize copper to copper cations.


Questions



is CuBr soluble in water

Copper bromide (CuBr) is not soluble in water.



What is the Cuprous ion formula?

Cu+







Amphoteric nature of water NO2- lewis structure N2O lewis structure, resonance structures Stability of water







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