Transition metal colours

• MnO4 -


  Purple
• Mn 2+


  Pale pink (almost colourless)
• Cr2O7 2-


  Orange
• Cr 3+


  green
• [Cu(H2O)6]2+


  Pale blue
• CoCl4 2-


  Blue
• Cu(OH)2


  Pale blue ppt
• [Cr(H2O)6] 3+


  Pale purple, green due to impurities
• [Cu(NH3)4(H2O)2]2+


  Dark blue
• Cr(H2O)3 


  Dark green ppt
• CuCl4 2-


  Yellow
• [Cr(NH3)6] 3+


  Purple
• Reduction of Cu2+ with I-

  White ppt of CuI and brown I2 solution
• [Cr(OH)6]3-

  Dark green
• Disproportionation of Cu+


  Brown solid of Cu and blue solution of CuSO4
• CrO4 2-


  Yellow
• Fe(OH)3


  Orange brown ppt
• [Mn(H2O)6]2+


  Pale pink
• Mn(OH)2


  Pale brown ppt
• [Fe(H2O)6]2+


  Pale green
• Fe(OH)2


  Dark green ppt
• [Fe(H2O)6]3+


  Yellow
• Co 2+


  Pink solution, blue ppt
• [Co(H2O)6]2+

  Pink
• [Co(NH3)6]2+

  Straw yellow