AQA A Level Chemistry Transition Metals - Colours

Colour of MnO4- (+7 oxidation state)

purple

Colour of CrO7 2- (+6 oxidation state)

orange

Colour of V(O2)+ (+5 oxidation state)

yellow

Colour of VO 2+ (+4 oxidation state)

blue

Colour of V 3+ (+3 oxidation state)

green

Colour of Cr 3+ (+3 oxidation state)

green/violet

Colour of Fe 3+ (+3 oxidation state)

yellow

Colour of V 2+ (+2 oxidation state)

violet

Colour of Mn 2+ (+2 oxidation state)

pale pink

Colour of Fe 2+ (+2 oxidation state)

pale green

Colour of Co 2+ (+2 oxidation state)

pink

Colour of Ni 2+ (+2 oxidation state)

green

Colour of Cu 2+ (+2 oxidation state)

blue

Cr 3+ are violet when...

they are surrounded by 6 water ligands

Cr 3+ are green when...

the 6 water ligands are substituted

If [Cu(H2O)6]2+ absorbs light from the red end of the spectrum...

blue will be produced

Colour of [Fe(H2O)6]2+

pale green

Colour of [Fe(H2O)6]3+

yellow

Colour of [V(H2O)6]2+

violet

Colour of [V(H2O)6]3+

green

Colour of [Cu(H2O)6]2+

blue

Colour of [CuCl4]2-

yellow

Colour of [Co(H2O)6]2+

pink

Colour of [Co(NH3)6]2+

straw coloured

[Cu(H2O)6]2+ with OH- or NH3

blue ppt

[Cu(H2O)6]2+ with excess OH-

no change

[Cu(H2O)6]2+ with excess NH3

deep blue solution

[Cu(H2O)6]2+ with Na2CO3

green-blue ppt

[Fe(H2O)6]2+ with OH- or NH3

green ppt

[Fe(H2O)6]2+ with excess OH-

no change

[Fe(H2O)6]2+ with excess NH3

no change

[Fe(H2O)6]2+ with Na2CO3

green ppt

[Al(H2O)6]3+ with OH- or NH3

white ppt

[Al(H2O)6]3+ with excess OH-

colourless solution

[Al(H2O)6]3+ with excess NH3

no change

[Al(H2O)6]3+ with Na2CO3

white ppt

[Fe(H2O)6]3+ with OH- or NH3

brown ppt

[Fe(H2O)6]3+ with excess OH-

no change

[Fe(H2O)6]3+ with excess NH3

no change

[Fe(H2O)6]3+ with Na2CO3

brown ppt