Complex ions, ligands and shapesEdexcel International A Level Chemistry: Mind map

Exam questions on Complex ions, ligands and shapes

1. When an excess of aqueous ammonia is added to aqueous copper(II) sulfate, some of the water ligands around the copper(II) ion are replaced and the complex ion [Cu(NH₃)₄(H₂O)₂]²⁺ forms.
   Explain why ammonia is able to act as a ligand.2 marks
2. Cobalt(II) ions form the complex ion [Co(H₂O)₆]²⁺ in water. When concentrated hydrochloric acid is added, the complex ion [CoCl₄]²⁻ forms.
   Suggest why the cobalt(II) ion bonds to four chloride ligands but to six water ligands.2 marks
3. Cisplatin, [Pt(NH₃)₂Cl₂], is a neutral, square planar complex of platinum used in cancer treatment. It is supplied to hospitals as a single isomer.
   State the coordination number of platinum in cisplatin and deduce the oxidation number of platinum in it. State the shape of the complex.3 marks