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