Reaction of aqueous ions

Question 1

Define ligand

Answer 1

Ion with a lone pair of electrons which can form a co-ordinate bond with a metal ion

Question 2

What is the formula and colour of the iron (II) aqueous ion?

Answer 2

[Fe(H2O)6]2+
green solution

Question 3

What is the formula and colour of the copper (II) aqueous ion?

Answer 3

[Cu(H2O)6]2+
blue solution

Question 4

What is the formula and colour of the iron (III) aqueous ion?

Answer 4

[Fe(H2O)6]3+
purple solution

Question 5

What is the formula and colour of the aluminium (III) aqueous ion?

Answer 5

[Al(H2O)6]3+
colourless solution

Question 6

Why are the 3+ ions more acidic than the 2+ ions? (6)

Answer 6

• Fe3+ has a higher charge and is smaller than 2+
• Fe3+ is more polarising
• Fe3+ strongly attracts the lone pair on the oxygen of water ligands
• This weakens the strength go the O-H bond
• Fe(III) complex more easily releases H+ ions making the solution acidic
• Fe(II) complex doesn’t release H+ ions