Reactions of aqueous ions

Define a Lewis acid

Electron pair acceptor

Define a Lewis base

Electron pair donator

In complex ions, why is the ligand the Lewis base?

It is donating a pair of electrons in the dative covalent bond (the metal ion is the Lewis acid)

Give the formulae of 2+ metal aqua ions

[M(H2O)6] 2+

Give the formulae of 3+ metal aqua ions

[M(H2O)6] 3+

Give the equation for the equilibrium that occurs in aqueous solutions of 2+ metal ions

[M(H2O)6] 2+ + H2O <=> [M(H2O)5(OH)]+ + H3O+

Give the equation for the equilibrium that occurs in aqueous solutions of 3+ metal ions

[M(H2O)6] 3+ + H2O <=> [M(H2O)5(OH)]2+ + H3O+

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

3+ metal ions have a higher charge density (charge/size ratio) and have greater polarising power meaning it more strongly attracts the water molecule, weakening the O-H bond and making it more easily release H+ ions

Colour of ion and formula of product when add OH- or NH3 to aqueous solution - Cu2+

Pale blue precipitate

Cu(OH)2(H2O)4 (s)

Colour of ion and formula of product when add OH- or NH3 to aqueous solution - Fe2+

Dirty green precipitate

Fe(OH)2(H2O)4 (s)

Colour of ion and formula of product when add OH- or NH3 to aqueous solution - Fe3+

Orange precipitate

Fe(OH)3(H2O)3 (s)

Colour of ion and formula of product when add OH- or NH3 to aqueous solution - Al3+

White precipitate

Al(OH)3(H2O)3 (s)

Colour of ion and formula of product when add excess OH- to precipitate - Cu2+

Insoluble in excess NaOH (no change)

Colour of ion and formula of product when add excess OH- to precipitate - Fe2+

Insoluble in excess NaOH (no change)

Colour of ion and formula of product when add excess OH- to precipitate - Fe3+

Insoluble in excess NaOH (no change)

Colour of ion and formula of product when add excess OH- to precipitate - Al3+

Colourless solution

[Al(OH)4]- (aq)

Colour of aqueous ion in solution - Cu2+

Blue

Colour of aqueous ion in solution - Fe2+

Pale green

Colour of aqueous ion in solution - Fe3+

Orange

Colour of aqueous ion in solution - Al3+

Colourless

Colour of ion and formula of product when add excess NH3 to the precipitate - Cu2+

Dark blue solution

[Cu(NH3)4(H2O)2] 2+ (partial substitution)

Colour of ion and formula of product when add excess NH3 to the precipitate - Fe2+, Fe3+ and Al3+

Insoluble in excess NH3 (no change)

Colour of ion and formula of product when add Na2CO3 (aq) - Cu2+

Green-blue precipitate

CuCO3 (s)

Colour of ion and formula of product when add Na2CO3 (aq) - Fe2+

Green precipitate

FeCO3 (s)

Colour of ion and formula of product when add Na2CO3 (aq) - Fe3+

Brown precipitate

Fe(OH)3(H2O)3 (s)

Colour of ion and formula of product when add Na2CO3 (aq) - Al3+

White precipitate

Al(OH)3(H2O)3 (s)

What is observed when Na2CO3 (aq) is added to aqueous solutions of Fe3+ and Al3+

Bubbles of gas (CO2)

Colour of ion and formula of product when add conc. HCl - Cu2+

Green solution

[CuCl4]2-

Colour of ion and formula of product when add conc. HCl - Fe2+

Yellow solution

[FeCl4]2-

Colour of ion and formula of product when add conc. HCl - Fe3+

Yellow solution

[FeCl4]-

Colour of ion and formula of product when add conc. HCl - Al3+

Colourless solution

[AlCl4]-