Reactions of Ions in Aqueous Solution Flashcards
Define a lewis acid
Electron pair acceptor
Define a lewis base
Electron pair donor
Explain what the ligand in the formation of complex ions acts as and why
The ligand is the Lewis base because it is donating a pair of electrons in the dative covalent bond and the metal ion is the Lewis acid
What metals form the metal aqua ions [M(H2O)6]2+ in aqueous solution
M = Fe (green) and Cu (blue)
What metals form the metal aqua ions [M(H2O)6]3+ in aqueous solution
Al (colourless) and Fe (violet)
What is the acidity or hydrolysis reactions which happen in aqueous solutions of metal ions
[M(H2O)6]2+ + H2O = [M(H2O)5(OH)]+ + H3O+
IT IS A REVERSIBLE REACTION
State and explain the difference in acidity of [M(H2O)6]3+ and [M(H2O)6]2+
[M(H2O)6]3+ is more acidic.
The 3+ metal ions have a higher charge density and have greater polarising power.
The greater the polarising power, the more strongly it attracts the water molecule.
This weakens the O-H bond so it breaks more easily and releases H+ ions.
Colour of [Fe(H2O)6]2+
Green solution
Colour of [Cu(H2O)6]2+
Blue solution
Colour of [Fe(H2O)6]3+
Purple solution
Colour of [Al(H2O)6]3+
Colourless solution
Colour of Fe(H2O)4(OH)2
Green precipitate which goes brown on standing in air
Colour of Cu(H2O)4(OH)2
Blue precipitate
Colour of Fe(H2O)3(OH)3
Brown precipitate
Colour of Al(H2O)3(OH)3
White precipitate
Equation for the reaction between [Fe(H2O)6]2+ and NaOH
[Fe(H2O)6] 2+ (aq) + OH– (aq) → [Fe(H2O)5(OH)] + (aq) + H2O (l)
[Fe(H2O)5(OH)] + (aq) + OH– (aq) → Fe(H2O)4(OH)2 (s) + H2O (l)
OR full equation :
[Fe(H2O)6] 2+(aq) + 2OH– (aq) → Fe(H2O)4(OH)2 (s) + 2H2O (l)
Equation for the reaction between [Cu(H2O)6]2+ and NaOH
[Cu(H2O)6] 2+ (aq) + 2OH– (aq) → Cu(H2O)4(OH)2 (s) + 2H2O (l)
Equation for the reaction between [Fe(H2O)6]3+ and NaOH
[Fe(H2O)6]3+ (aq) + 3OH– (aq) → Fe(H2O)3(OH)3 (s) + 3H2O (l)
Equation for the reaction between [Al(H2O)6]3+ and NaOH
[Al(H2O)6]3+ (aq) + 3OH– (aq) → Al(H2O)3(OH)3 (s) + 3H2O (l)
What happens when excess NaOH is added to the aqueous solutions of metal ions
No further change with :
Iron (II)
Copper (II)
Iron (III)
forms colourless solution of [Al(OH)4]- with Al (III)
Equation for aluminium hydroxide dissolving in excess NaOH
Al(OH)3(H2O)3 (s) + NaOH (aq) → Na [Al(OH)4] (aq) + 3H2O (l)
Equation for aluminium hydroxide reacting with and dissolving in dilute HCl
Al(OH)3(H2O)3 (s) + 3HCl (aq) → [Al(H2O)6] 3+ (aq) + 3Cl- (aq)
Equation for reaction between aqueous solution of Cu(II) and NH3 (aq)
[Cu(H2O)6] 2+ (aq) + 2NH3 (aq) → Cu(H2O)4(OH)2 (s) + 2NH4+ (aq)
SAME PRODUCT FORMED AS WITH NAOH
Equation for reaction between aqueous solution of Fe(III) and NH3 (aq)
[Fe(H2O)6] 3+ (aq) + 3NH3 (aq) → Fe(H2O)3(OH)3 (s) + 3NH4+ (aq)
SAME PRODUCT FORMED AS WITH NAOH
What reaction occurs when excess NH3 is added to Copper (II) in aqueous solution
Ligand substitution
Reaction of copper (II) with excess NH3
Cu(H2O)4(OH)2 (s) + 4NH3 (aq) → [Cu(NH3)4(H2O)2 ]2+ (aq) + + 2OH- (aq) + 2H2O (l)
Colour of [Cu(NH3)4(H2O)2 ]2+
Deep blue solution
Reaction of Iron (II), Iron (III) and Al (III) with excess NH3
No further change
Colour of FeCO3 (s)
Green precipitate
Colour of CuCO3 (s)
Blue-green precipitate
Equation for the reaction between aqueous iron (II) ions and Na2CO3
[Fe(H2O)6] 2+ (aq) + CO32- (aq) → FeCO3 (s) + 6H2O (l)
Equation for the reaction between aqueous copper (II) ions and Na2CO3
[Cu(H2O)6] 2+ (aq) + CO32- (aq) → CuCO3 (s) + 6H2O (l)
Equation for the reaction between aqueous aluminium (III) ions and Na2CO3
2[Al(H2O)6]3+ + 3CO32− (aq) → 2Al(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l)
Equation for the reaction between aqueous iron (III) ions and Na2CO3
2[Fe(H2O)6]3+ (aq) + 3CO32− (aq) → 2Fe(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l)
What is formed when M (II) ions react with conc HCL
[MCl4]2-
Colour of [FeCl4]2-
Yellow solution
Colour of [CuCl4]2-
green solution
Colour of [FeCl4]-
Yellow solution
Colour of [AlCl4]-
Colourless solution
