Mr Cole Chemistry

Reactions of Aqueous Copper Ions

  • Questions
  • Answers
  1. For the following reactants, write the equation for the for the reaction; state what you would observe during the reaction; and state the type of reaction.
    1. Copper(II) sulfate and sodium hydroxide.
    2. Copper(II) sulfate and excess ammonia.
    3. Copper(II) sulfate and limited ammonia.
    4. Copper(II) sulfate and sodium carbonate.
    5. Copper(II) hydroxide and an acid.
    6. Copper(II) sulfate and chloride ions.
  2. The following colour changes occurred. Suggest the equation for the reaction that occurred
    1. Blue solution –> dark blue solution
    2. Blue solution –> green solution
    3. Blue solid –> dark blue solution
    4. Blue –> blue-green precipitate
    5. Blue –> blue precipitate
    6. Blue-green solid –> green solution
  1. For the following reactants, write the equation for the for the reaction; state what you would observe during the reaction; and state the type of reaction.
    1. Copper(II) sulfate and sodium hydroxide.
      [Cu(H2O)6]2+ + 2OH– –> Cu(H2O)4(OH)2 + 2H2O
      You would observe the blue solution becoming a blue precipitate.
      The reaction is a hydrolysis reaction.
    2. Copper(II) sulfate and excess ammonia.
      [Cu(H2O)6]2+ + 4NH3 –> [Cu(NH3)4(H2O)2]2+ + 4H2O
      You would observe the blue solution becoming a dark blue solution.
      The reaction is a ligand substitution reaction.
    3. Copper(II) sulfate and limited ammonia.
      [Cu(H2O)6]2+ + CO32- –> CuCO3 + 6H2O
      You would observe the blue solution becoming a blue-green solution.
      The reaction is a precipitation reaction.
    4. Copper(II) sulfate and sodium carbonate.
      Cu(H2O)4(OH)2 + 2H+ –> [Cu(H2O)6]2+
      You would observe the blue precipitate dissolving to form a blue solution.
      This reaction is a neutralisation reaction.
    5. Copper(II) hydroxide and an acid.
      [Cu(H2O)6]2+ + 2NH3 –> Cu(H2O)4(OH)2 + 2NH4+
      You would observe the blue solution becoming a blue precipitate.
      The reaction is a hydrolysis reaction.
    6. Copper(II) sulfate and chloride ions.
      [Cu(H2O)6]2+ + 4Cl– –> [CuCl4]2- + 6H2O
      You would observe the blue solution becoming a yellow solution.
      The reaction is a ligand substitution reaction.
  2. The following colour changes occurred. Suggest the equation for the reaction that occurred
    1. Blue solution –> dark blue solution
      [Cu(H2O)6]2+ + 4NH3 –> [Cu(NH3)4(H2O)2]2+ + 4H2O
    2. Blue solution –> green solution
      [Cu(H2O)6]2+ + 4Cl– –> [CuCl4]2- + 6H2O
    3. Blue solid –> dark blue solution
      Cu(H2O)4(OH)2 + 4NH3 –> [Cu(NH3)4(H2O)2]2+ + 2H2O + 2OH–
    4. Blue –> blue-green precipitate
      [Cu(H2O)6]2+ + CO32- –> CuCO3 + 6H2O
    5. Blue –> blue precipitate
      [Cu(H2O)6]2+ + 2OH– –> Cu(H2O)4(OH)2 + 2H2O
      [Cu(H2O)6]2+ + 2NH3 –> Cu(H2O)4(OH)2 + 2NH4+
    6. Blue-green solid –> green solution
      CuCO3 + 4HCl –> CO2 + H2O + [CuCl4]2- + 2H+
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