Transition metals // Complex ions

Question 1

Why are the chloride ions in [Cu(H2O)6]Cl2 are not considered to be ligands?

Answer 1

Because they are not covalently bonded to the transition metal - there is no donating of a lone pair of electrons

Question 2

An excess of Ammonia is added to [Cu(H2O)6]Cl2, what is the ionic equation for this reaction, and what colour is the end solution?

Answer 2

[Cu(H2O)6]2+ + 4NH3 —> Cu(NH3)4(H2O)2 + 4H20

Deep blue

Question 3

Explain why colourimetry cannot be used to determine the concentration of solutions containing [CuCl2]-

Answer 3

Its colourless, as it doesn’t have a partially filled D sub shell

Question 4

Hexaaquairon(iii) ions react with an excess of hydrochloric acid in a ligand substitution reaction, what is the equation for this reaction?

Answer 4

[Fe(H2O)6]3+ 4Cl- —> [FeCl4]- + 6H2O

Question 5

What is the ionic equation for the reaction of iron(ii) ions with manganate(vii) ions?

Answer 5

5Fe2+ + MnO4- + 8H+ —> Mn2+ + 5Fe3+ + 4H2O

Question 6

[Cu(H2O)6]2+ reacts to form a copper-containing species that is a pale blue precipitate, name the reagent that it reacts with, the species it makes and the equation of the reaction.

Answer 6

[Cu(H2O)6]2+ +2NH3 —> Cu(H2O)4(OH)2 + 2[NH4]+

Dilute NH3