Reactions Of Metal Aqua Ions

• Metal ions become hydrated in water (H2O ligands around a central ion) and they form coloured precipitates that can be used to identify the metal ion present.
• When ions are in solution they are acidic, 3+ ions are more acidic than 2+ because they dissociate more so have a greater attractive power to OH-.
• Metal ions in solution react as acids with NaOH in a neutralisation reaction to form a salt and water.
• Aluminium salt can act as an acid or a base meaning it is amphoteric.
• Metal ions react with aqueous ammonia to form a salt and ammonium ions.
• Solutions of these metal 2+ ions react with sodium carbonate as acids forming insoluble carbonates and water.
• Solutions of metal 3+ ions act as stronger acids so they react with sodium carbonate to form a salt, water and carbon dioxide.
• All metal aqua ions undergo ligand substitution when reacted with chlorine ions to form tetrahedral ions with four chlorine ligands (occurs when they react with concentrated HCl).
• 3+ ions form stronger acids as they have a larger charge density so are more polarising and can break O-H bonds more easily.
• Sodium and magnesium oxide form alkaline solutions because they react with water to produce hydroxide ions. However, sodium hydroxide is more soluble than magnesium hydroxide (dissociates more).
• In the contact process, vanadium oxide is used as a catalyst to convert sulfur dioxide to sulfur trioxide.

  
• Complexes formed from transition metal ions are coloured because they absorb some wavelengths of visible light which excites the electrons in the d-orbitals so the remaining wavelengths of light are transmitted to give out colour.