Transition Element Colours

• Cr3+ + NaOH complex ion

  [Cr(H2O)6]3+

  Violet solution
• Cr3+ + OH-


  Cr(OH)3(H2O)3

  Green precipitate
• Cr3+ with excess OH-

  [Cr(OH)6]3-

  Green solution
• Fe2+ + NaOH complex ion

  [Fe(H2O)6]2+

  Green solution
• Fe2+ with OH-


  Fe(OH)2(H2O)4

  Green precipitate
• Fe3+ + NaOH complex ion

  [Fe(H2O)6]3+

  Yellow solution
• Fe3+ with OH-


  Fe(OH)3(H2O)3

  Brown precipitate
• Mn2+ + NaOH complex ion


  [Mn(H2O)6]2+

  Pale pink solution
• Mn2+ with OH-


  Mn(OH)2(H2O)4

  Pale brown precipitate
• Cu2+ + NaOH complex ion


  [Cu(H2O)6]2+

  Blue solution
• Cu2+ with OH-


  Cu(OH)2(H2O)4

  Blue precipitate
• Cr3+ + NH3 complex ion

  [Cr(H2O)6]3+

  Violet solution
• Cr3+ with NH3


  Cr(OH)3(H2O)3

  Green precipitate
• Cr3+ with excess NH3

  [Cr(NH3)6]3+

  Purple solution
• Fe2+ + NH3 complex ion

  [Fe(H2O)6]2+

  Green solution
• Fe2+ with NH3


  Fe(OH)2(H2O)4

  Green precipitate
• Fe3+ + NH3 complex ion

  [Fe(H2O)6]3+

  Yellow solution
• Fe3+ with NH3


  Fe(OH)3(H2O)3

  Brown precipitate
• MN2+ + NH3 complex ion

  [Mn(H2O)6]2+

  Pale pink solution
• Mn2+ with NH3


  Mn(OH)2(H2O)4

  Pale brown precipitate
• Cu2+ + NH3 complex ion

  [Cu(H2O)6]2+

  Blue solution
• Cu2+ with NH3


  Cu(OH)2(H2O)4

  Blue precipitate
• Cu2+ with excess NH3

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

  Dark blue solution
• Cl- + AgNO3


  White precipitate of AgCl
• Cl- + dilute NH3


  White AgCl precipitate dissolves
• Cl- + conc NH3


  White AgCl precipitate dissolves
• Br- + AgNO3


  Cream precipitate of AgBr
• Br- + dilute NH3

  No change
• Br- + conc NH3

  Cream AgBr precipitate dissolves
• I- + AgNO3


  Yellow precipitate of AgI
• I- + any conc of NH3

  No change