6. reactions of ions in aqueous solutions

• What happens to metal aqua complexes when a transition metal compound is added to water?

  They are formed with six water ligands
• What type of bond is formed between water ligands and metal ions?

  Coordinate bonds
• How many water ligands surround a transition metal ion in a complex?

  Six water ligands
• What is the effect of the charge on metal aqua ions?

  It affects their acidity in solution
• What happens to iron(II) ions when dissolved in water?

  They form a complex with six water ligands
• What does the formation of H3O+ indicate about a solution?

  It indicates the solution is acidic
• What is the term for the reaction that involves breaking down a complex using water?

  Hydrolysis
• Why are Fe(III) complexes more acidic than Fe(II) complexes?

  They dissociate more readily in solution
• How does charge density affect the acidity of metal ions?

  Higher charge density increases acidity
• What happens to the bond between water and metal ions in higher charged complexes?

  The bond becomes weaker and more susceptible to break
• What ions can be used to hydrolyze metal aqua ions further?

  Hydroxide ions (OH-)
• What is formed when metal aqua ions are hydrolyzed with hydroxide ions?

  Insoluble metal hydroxides
• What happens to the charge of a complex when it becomes neutral?

  It becomes insoluble and forms a precipitate
• What is the significance of writing equations for hydrolysis of metal hydroxides?

  It helps understand the reaction process
• What is formed when water reacts with metal hydroxides?

  A neutral complex
• Why does a neutral complex become solid?

  It becomes insoluble when neutral
• What is hydrolysis of metal hydroxides?

  It involves the reaction with water
• How many hydroxides are needed for a metal with a +3 charge?

  Three hydroxides
• How many steps are involved in hydrolyzing metal aqua 2+ ions?

  Two steps
• What happens when more hydroxide ions are added to a metal aqua 2+ complex?

  It shifts equilibrium to the right
• What are amphoteric metal hydroxides?

  They can act as acids or bases
• How do amphoteric metal hydroxides behave in excess acid?

  They dissolve by accepting protons
• What is a common example of an amphoteric metal hydroxide?

  Aluminium hydroxide
• What happens when aluminium hydroxide acts as a Bronsted-Lowry acid?

  It donates a proton to a base
• What is formed when aluminium hydroxide reacts with a base?

  Aluminium hydroxide complex
• What occurs when aluminium hydroxide reacts with an acid?

  It accepts protons to dissolve
• What is produced when metal aqua ions react with ammonia?

  Metal hydroxide precipitates
• What happens when excess ammonia is added to metal aqua ions?

  It can lead to ligand exchange
• What is the result of adding small amounts of ammonia to metal aqua ions?

  Same metal hydroxides as hydroxide addition
• What happens when excess ammonia is added to copper complexes?

  Some ligands are displaced
• How do 2+ and 3+ metal ions differ in their reaction with carbonates?

  2+ forms metal carbonates; 3+ does not
• What is produced when 2+ metal aqua ions react with sodium carbonate?

  Metal carbonate precipitates
• What happens when 3+ metal ions react with carbonates?

  They form hydroxide complexes
• How can you distinguish between 2+ and 3+ metal complexes using carbonates?

  2+ shows no fizzing; 3+ produces CO2
• What indicates a 3+ metal complex when reacting with carbonates?

  Production of carbon dioxide
• What indicates a 2+ metal complex when reacting with carbonates?

  No fizzing occurs
• What type of reaction involves a 3 plus reactant with carbonate?

  Formation of hydroxide complex
• What is produced when a 3 plus metal reacts with carbonate?

  Carbon dioxide and water
• How can you distinguish between a 3 plus and 2 plus metal complex using carbonate?

  Fizzing indicates a 3 plus complex
• What are the steps to test metal ions with sodium hydroxide, ammonia, and sodium carbonate?

  1. Add unknown metal solution to three test tubes.
  2. Add sodium hydroxide drop by drop to tube one.
  3. Observe and then add excess sodium hydroxide.
  4. Repeat with ammonia in tube two.
  5. Finally, add sodium carbonate drop by drop in tube three.