Aqueous metal ions

• Metal-aqua ions are complex ions tha t only contain water ligands
• [Al(H2O)6]3+ - colourless solution

  [Fe(H2O)6]3+ - brown yellow solution

  [Cu(H2O)6]2+ - blue solution

  [Fe(H2O)6]2+ - green solution
• Metal-aqua ions are acidic as they release protons into water

  [Al(H2O)6]3+ + H2O -> [Al(H2O)5(OH)]3+ + H3O+

  As Al3+ draws elctrons from the Al-O and O-H bonds. This results in the hydrogen atoms having a greater partial positive charge
• 3+ ions are more acidic than 2+ ions

  As 3+ has a higher charge so its electrons are more attracted to the nucleus and thus it has a smaller ionic radius so it has a higher charge/size ratio so the dative covalent bonds are more attracted to it so the H atoms have a greater partial positive charge so the bonds break easier