THEORY

Question 1

(a) manganate(VII) titrations; non-structured calculations based on these and any other types of titration

Question 2

(i) the terms ligand, complex/complex ion and ligand substitution
Learners should know the formulae of the following examples of complex ions from the chemistry of: iron: [Fe(H2O)6] 2+, [Fe(H2O)6] 3+; and copper: [Cu(H2O)6] 2+, [Cu(NH3) 4] 2+, [CuCl 4] 2–. They should be able to write similar formulae for other complexes, given suitable information. • test-tube or reduced scale reactions involving iron, copper and other transition metals and their compounds, including the formation of complex ions

Question 3

(k) the colour changes in, and ionic equations for, the reactions of: Fe²⁺_(aq), Fe³⁺_(aq) and Cu²⁺_(aq) ions with sodium hydroxide solution and ammonia solution
[Iron(II) hydroxide and iron(III) hydroxide do not form complexes with ammonia.]

AMMONIA REACTION

Answer 3

• Fe²⁺_(aq) + 2OH^-_(aq) –> Fe(OH)_2(s)
  
  • Iron(II) hydroxide = dark green gelatinous precipitate
  • _​OH^- ions come from NaOH
  • Do not form complexes with ammonia
• Fe³⁺_(aq) + 3OH^-_(aq) –> Fe(OH)_3(s)
  
  • Iron(III) hydroxide = orange/red-brown gelatinous precipitate
  • _​OH^- ions come from NaOH
  • Do not form complexes with ammonia
• Cu²⁺_(aq) + 2OH^-_(aq) –> Cu(OH)_2(s)
  
  • Copper(II) hydroxide = pale blue precipitate
  • _​OH^- ions come from NaOH