reactions of aqueous ions

• [M(H2O)6]2+ + H2O


  [M(H2O)5(OH)]+ + H3O+
• Reactions of Inorganic Compounds in Aqueous Solution
• Lewis acid


  Electron pair acceptor
• Lewis base


  Electron pair donator
• In the formation of complex ions the ligand is the Lewis base because it is donating a pair of electrons in the dative covalent bond and the metal ion is the Lewis acid
• Metal-aqua ions


  Metal aqua ions are formed in aqueous solution
• [M(H2O)6]2+


  • [Fe(H2O)6]2+ (green), [Cu(H2O)6]2+ (blue)
• [M(H2O)6]3+


  • [Al(H2O)6]3+ (colourless), [Fe(H2O)6]3+ (violet)
• In solution Fe(III) appears yellow/brown due to hydrolysis reactions. The violet colour is only really seen in solid hydrated salts that contain these complexes
• The acidity of [M(H2O)6]3+ is greater than that of [M(H2O)6]2+ because the 3+ metal ions have higher charge density (charge/size ratio) and have greater polarising power. The greater the polarising power, the more strongly it attracts the water molecule. This weakens the O-H bond so it breaks more easily releasing H+ ions
• [Cu(H2O)6]2+ + 2OH-


  Cu(H2O)4(OH)2 (s) + 2H2O
• [Al(H2O)6]3+ + 3OH-


  Al(H2O)3(OH)3 (s) + 3H2O
• [Fe(H2O)6]2+ + 2NH3


  Fe(H2O)4(OH)2 (s) + 2NH4+
• [Fe(H2O)6]3+ + 3NH3


  Fe(H2O)3(OH)3 (s) + 3NH4+
• [Al(H2O)6]3+ + OH-


  [Al(H2O)5(OH)]2+ + H2O
• Al(H2O)3(OH)3 (s) + OH-

  [Al(OH)4]- (aq)
• Al(H2O)3(OH)3 (s) + 3H+


  [Al(H2O)6]3+ (aq)
• Cu(OH)2(H2O)4(s) + 4NH3


  [Cu(NH3)4(H2O)2]2+ (aq) + 2H2O + 2OH-
• [Al(H2O)5(OH)]2+ + OH-


  [Al(H2O)4(OH)2]+ + H2O
• Cu2+ + CO3 2-


  CuCO3 (s)
• 2[Fe(H2O)6]3+ + 3CO3 2-

  2Fe(OH)3(H2O)3(s) + 3CO2 + 3H2O
• 2[Al (H2O)6]3+ + 3CO3 2-

  2Al(OH)3(H2O)3(s) + 3CO2 + 3H2O
• [Cu(H2O)6]2+ + CO3 2-


  CuCO3 + 6H2O
• [Fe(H2O)6]2+ + CO3 2-


  FeCO3 + 6H2O