colours of inorganic ions and complexes

[Cu(H2O)]2+

pale blue solution

Cu(OH)2

pale blue precipitate

[Cu(NH3)4(H2O)2]2+

dark blue solution

CuCl4 2-

yellow solution (1)

reducing Cu2+ with I-

white precipitate (CuI) and brown solution (I2)

reaction of Cu+ and H2SO4

brown precipitate (Cu) blue solution (CuSO4)

CoCl4 2-

blue solution

[Cr(H2O)6]3+

pale purple, green when heated

Cr(OH)3

dark green precipitate (1)

[Cr(NH3)6]3+

purple solution

[Cr(OH)6]3-

dark green solution

Cr2O7^2-

orange solution

CrO4^2-

yellow solution (2)

[Mn(H2O)6]²⁺

pale pink solution

Mn(OH)2

pale brown precipitate

[Fe(H20)6]²⁺

pale green solution

Fe(OH)2

dark green precipitate (2)

[Fe(H2O)6]³⁺

yellow solution (3)

Fe(OH)3

orange-brown precipitate

MnO4-/Fe2+→Mn2+/Fe3+

Purple to pale pink (may be colourless in titration)

I-/Fe3+→I2/Fe2+

orange brown (Fe3+) to brown (I2)