Reactions of Inorganic Ions in Aqueous Solutions

• What is a lewis acid?

  An electron pair acceptor
• What is a lewis base?

  An electron donor
• Is the ligand the lewis base or acid?

  Lewis base because it is donating a pair of electrons in a dative covalent bond
• How does Fe(III) appear in solution?

  Yellow/brown
• What is the equilibria equation for an M2+ ion?

  [M(H2O)6]2+ + H2O --> [M(H2O)5(OH-)]+ + H3O+
• What is the equilibria equation for an M3+ ion?

  [M(H2O)6]3+ + H2O --> [M(H2O)5(OH-)]2+ + H3O+
• Why is the solution with a 3+ ion more acidic than with a 2+ ion?

  • 3+ metal ions have a higher charge density
  • 3+ ions therefore have a greater polarising power
  • More strongly attracts the water molecule
  • Weakens O-H bond
  • Breaks more easily
  • Releases more H+ ions
  • Decreasing pH
• What is [Fe(H2O)6]2+?

  Green solution
• What colour is [Cu(H2O)6]2+?

  Blue solution
• What colour is [Al(H2O)6]3+?

  Colourless solution
• What colour is [Fe(H2O)6]3+ ?

  Purple solution but may look yellow-brown
• What colour is Cu(OH)2(H2O)4?

  Blue ppt
• What colour is Fe(OH)2(H2O)4 ?

  Green ppt
• What colour is Fe(OH)3(H2O)3?

  Brown ppt
• What colour is Al(OH)3(H2O)3?

  White ppt
• Why do some reaction form precipitates?

  Because precipitates have no charge
• Products of reaction of [Cu(H2O)6] with 2OH-?

  Cu(H2O)4(OH)2 + 2H2O
• Reaction of [Al(H2O)6]3+ with 3OH-?

  Al(H2O)3(OH)3 + 3H2O
• Products of reaction of [Fe(H2O)6]2+ with 2NH3?

  Fe(H2O)4(OH)2 + 2NH4+
• Products of reaction of [Fe(H2O)6]3+ and 3NH3?

  Fe(H2O)3(OH)3 (S)+ 3NH4+
• Give the two equations in order of [Al(H2O)6]3+ with OH- to form a solution, not a precipitate.

  [Al(H2O)6]3+ + OH- --> [Al(H2O)5(OH)]2+ (aq) + H2O

  [Al(H2O)5(OH)]2+(aq) + OH- --> [Al(H2O)4(OH)]+(aq) + H2O
• What happens to Al(H2O)3(OH)3 in excess NaOH?

  • Colourless solution is formed
  • Al(H2O)3(OH)3 + OH- --> [Al(OH)4]- + 3H2O
• Give a reaction of Al(H2O)3(OH)3 with H+?

  Al(H2O)3(OH)3 (s) + 3H+ --> [Al(H2O)6]3+(aq)
• What hydroxide is amphoteric?

  Al(H2O)3(OH)3
• What type of reaction occurs between Cu and excess NH3?

  Ligand substitution that is incomplete
• Give the equation for the reaction between Cu(OH)2(H2O)4 and excess NH3.

  Cu(OH)2(H2O)4 + 4NH3 --> [Cu(NH3)4(H2O)2]2+ + 2H2O + 2OH-
• What colour is [Cu(NH3)4(H2O)2]2+ ?

  Deep blue
• NH3 and OH- act as...

  Lewis bases by donating electron pairs
• What type of reactions is it with limited OH- and NH3?

  Acid-base
• What type of ion precipitates a carbonate ion?

  2+ due to 2- charge on CO32-
• What colour is CuCO3?

  Blue-green ppt
• What colour is FeCO3? (II)

  Green ppt
• Reactions for formation of CuCO3 and FeCO3?What type of reaction are they?

  Cu2+ + CO32- --> CuCO3

  Fe2+ + CO32- --> FeCO3

  
  

  Precipitation
• What is produced when 3+ ions react with CO32-?

  CO2 and M(OH)3 precipitate
• Equation for reaction of [Fe(H2O)6]2+ and CO32-?

  2[Fe(H2O)6]2+ + 3CO32- --> 2Fe(OH)3(H2O)3 (s) + 3CO2 + 3H2O
• Equation for the reaction of [Al(H2O)6]3+ and CO32-?

  2[Al(H2O)6]3+ + 3CO32- --> 2Al(H2O)3(OH)3 + 3CO2 + 3H2O
• Why is MCO3 formed with 2+ ions but M2(CO3)3 not formed with 3+ ions?

  3+ ion has greater polarising power as it has a higher charge density
• What colour is Fe(H2O)3(OH)3 ppt?

  Brown
• What colour is Al(H2O)3(OH)3 ppt?

  White
• What colour is [Al(OH)4]- ?

  colourless