Reactions of aqueous ions

lewis acid + lewis base definitions?

lewis acid - e- pair acceptor (metal ion)

lewis base - e- pair donor (ligand)

hydrolysis reactions of metal hex-aqua 2+ and 3+ ions?

colours for Cu, Fe(II), Fe(III), Al?

[M(H2O)6]2+(aq) + 2OH- <—> [M(H2O)4(OH)2](s) + 2H2O

[M(H2O)6]3+(aq) + 3OH- <—> [M(H2O)3(OH)3](s) + 3H2O

BLUE SOLN [Cu(H2O)6]2+ <—> BLUE PPT [Cu(H2O)4(OH)2](s)

GREEN SOLN [Fe(H2O)6]2+ <—> GREEN PPT [Fe(H2O)4(OH)2](s)

YELLOW SOLN [Fe(H2O)6]3+(aq) + 3OH- <—> BROWN PPT [Fe(H2O)3(OH)3](s) + 3H2O

COLOURLESS SOLN [Al(H2O)6]3+(aq) + 3OH- <—> WHITE PPT [Al(H2O)3(OH)3](s) + 3H2O

trend in acidity (2+ vs 3+ ions)?

• acidity of [M(H2O)6]3+ is greater than that of [M(H2O)6]2+

• 3+ metal ions have greater charge density + greater polarising power

• 3+ metal ions attract water molecules more strongly

  • weakens O-H bond so it breaks more easily + releases H+ ions

2+ and 3+ reactions with limited OH- or limited NH3 in acid-base reactions?

colours?

same as acidity reactions (example below):

[Fe(H2O)6]2+ (aq) + 2NH3 (aq) —> Fe(H2O)4(OH)2 (s) + 2NH4+(aq)

[Fe(H2O)6]3+ (aq) + 3NH3 (aq) —> Fe(H2O)3(OH)3 (s) + 3NH4+(aq)

same colours as acidity reactions

Al(H2O)3(OH)3(s) reactions with excess OH?

colours?

Al(H2O)3(OH)3(s) (WHITE) + OH- (aq ) —> [Al(OH)4]-(aq) (COLOURLESS) + 3H2O (l)

Al(H2O)3(OH)3(s) (WHITE) + 3H+ (aq ) —> [Al(H2O)6]3+ (aq)

AMPHOTERIC - ACTS AS ACID AND BASE

Cu ligand substitution reaction with excess NH3?

colour?

Cu(OH)2(H2O)4(s) + 4NH3(aq) —> [Cu(NH3)4(H2O)2]2+(aq) (DEEP BLUE) + 2H2O(l) + 2OH-(aq)

2+ ions with carbonate solution? (PRECIPITATION REACTIONS)

Results in MCO3 ppt being formed (Cu blue/green, Fe(II) green) (example below):

[Fe(H2O)6]2+ + CO3 2- —> FeCO3 + 6H2O

3+ ions with carbonate solution? (ACIDITY REACTIONS)

Form a M(OH)3 ppt and CO2 gas is evolved.

Al forms white ppt of Al(OH)3(H2O)3 + CO2

Fe(III) forms brown ppt of Fe(OH)3(H2O)3 + CO2