Colours

• What is the colour of [Fe(H2O)6] 3+ ?

  Yellow solution (actually purple but one of water ligands hydrolyses so appears yellow).
• [Fe(H2O)6] 3+ with OH- or NH3 =

  brown precipitate Fe(OH)3(H2O)3
• [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 precipitate & bubbles. Fe(OH)3(H2O)3
• What is the colour of [Cu(H2O)6] 2+ ?

  Blue solution
• [Cu(H2O)6] 2+ with OH- or NH3:

  blue precipitate Cu(OH)2(H2O)4
• [Cu(H2O)6] 2+ with excess OH-

  no change
• [Cu(H2O)6] 2+ with excess NH3

  deep blue solution [Cu(NH3)4(H2O)2] 2+
• [Cu(H2O)6] 2+ with Na2CO3 :

  green-blue precipitate CuCO3
• What is the colour of [Al(H2O)6] 3+ ?

  Colourless solution
• [Al(H20)6] 3+ with OH- or NH3

  white precipitate Al(OH)3(H20)3
• [Al(H2O)6] 3+ with excess OH-


  colourless solution [Al(OH)4]-
• [Al(H2O)6] 3+ with excess NH3

  no change
• [Al(H20)6] 3+ with Na2CO3

  white precipitate & bubbles. Al(OH)3(H2O)3
• What is the colour of [Fe(H2O)6] 2+ ?

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

  green precipitate (goes brown in air). Fe(OH)2(H2O)4
• [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 precipitate. FeCO3