Colours of Complex Ions

The colours of inorganic ions and complexes; information needed for OCR A Level Chemistry A Specification

colour resulting from dissolution of CuSO₄.5H₂O

pale blue

complex ion formed from dissolution of CuSO₄.5H₂O

[Cu(H₂O)₆]²⁺

colour resulting from addition of NH₃ (dropwise) to Cu²⁺ solution

pale blue precipitate

compound formed from addition of NH₃ (dropwise) to Cu²⁺ solution

Cu(OH)₂

colour resulting from addition of excess NH₃ to Cu²⁺ solution

dark blue

complex ion formed from addition of excess NH3 to Cu²⁺ solution

[Cu(NH₃)₄(H₂O)₂]²⁺

colour resulting from addition of excess HCl to Cu²⁺ solution

yellow

compound formed from addition of excess HCl to Cu²⁺ solution

CuCl₄^2-

colour resulting from reduction of Cu²⁺ with I^-

white precipitate (CuI) + brown liquid (I₂)

ion formed from reduction of Cu²⁺ with I^-

Cu⁺

colour resulting from disproportionation of Cu⁺ solution

brown solid (Cu) + blue solution (CuSO₄)

species resulting from disproportionation of Cu⁺ solution

Cu²⁺/Cu

colour resulting from addition of water and excess HCl to CoCl₂.6H₂O

blue

compound formed from addition of water and excess HCl to CoCl₂.6H₂O

CoCl₄ ^2-

colour resulting from dissolution of KCr(SO₄)2.12H₂O

pale purple (common for Cr(III) to appear green in solution due to impurities)

complex ion formed from dissolution of KCr(SO₄)₂.12H₂O

[Cr(H₂O)₆]³⁺

colour resulting from addition of NH₃ (dropwise) to Cr³⁺ solution

dark green precipitate

compound formed from addition of NH₃ (dropwise) to Cr³⁺ solution

Cr(OH)₃

colour resulting from addition of excess NH₃ to Cr³⁺ solution

purple

complex ion formed from addition of excess NH₃ to Cr³⁺ solution

[Cr(NH₃)₆]³⁺

colour resulting from addition of excess OH- to Cr(OH)₃

dark green

complex ion formed from addition of excess OH- to Cr(OH)₃

[Cr(OH)₆]^3-

colour resulting from addition of K₂Cr₂O₇ to 0.1moldm^-3 HCl

orange

ion formed from addition of K₂Cr₂O₇ to 0.1moldm^-3 HCl

Cr₂O₇^2-

colour resulting from oxidation of Cr³⁺ with hot alkaline H₂O₂

yellow

ion formed from oxidation of Cr³⁺ with hot alkaline H₂O₂

CrO₄^2-

colour resulting from dissolution of MnSO₄.4H₂O

pale pink

complex ion formed from dissolution of MnSO₄.4H₂O

[Mn(H₂O)₆]²⁺

colour resulting from addition of NaOH dropwise to Mn²⁺ solution

pale brown precipitate

compound formed from addition of NaOH dropwise to Mn²⁺ solution

Mn(OH)₂

colour resulting from dissolution of FeSO₄.7H₂O

pale green

complex ion formed from dissolution of FeSO₄.7H₂O

[Fe(H₂O)₆]²⁺

colour resulting from addition of NaOH dropwise to Fe²⁺solution

dark green precipitate

compound formed from addition of NaOH dropwise to Fe²⁺ solution

Fe(OH)₂

colour resulting from dissolution of FeCl₃.6H₂O

yellow

complex ion formed from dissolution of FeCl₃.6H₂O

[Fe(H₂O)₆]³⁺

colour resulting from addition of NaOH dropwise to Fe³⁺ solution

orange-brown precipitate

compound formed from addition of NaOH dropwise to Fe³⁺ solution

Fe(OH)₃

colour change resulting from oxidation of MnO₄^- by Fe²⁺

purple to pale pink

products of oxidation of MnO₄^- by Fe²⁺

Mn²⁺ & Fe³⁺

colour change resulting from reduction of Fe³⁺ by I^-

orange brown to brown

products of reduction of Fe³⁺ by I^-

I₂ & Fe²⁺