Reactions of transition metal ions with bases and ligandsEdexcel A-Level Chemistry: Flashcards
What these 14 flashcards ask
- What is seen when NaOH is added to Cu²⁺(aq), dropwise then in excess?
- What is seen when NH₃ is added to Cu²⁺(aq), dropwise then in excess?
- What is seen when NaOH is added to Cr³⁺(aq) in excess?
- What is seen with Fe²⁺(aq) and NaOH?
- What is seen with Fe³⁺(aq) and NaOH?
- What is seen with Co²⁺(aq) and NaOH, then excess NH₃?
- What does amphoteric mean?
- Write the equation for the amphoteric reaction of Cr(OH)₃(H₂O)₃ with excess OH⁻.
- How do ligand exchange and amphoteric behaviour differ?
- Write the equation for [Cu(H₂O)₆]²⁺ and NH₃ forming the deep blue ion.
- Why does the coordination number fall when Cl⁻ replaces H₂O?
- What colour change occurs in [Co(H₂O)₆]²⁺ → [CoCl₄]²⁻?
- Why is a complex with a bidentate ligand more stable than one with monodentate ligands?
- How many particles change in [Ni(H₂O)₆]²⁺ + 3en → [Ni(en)₃]²⁺ + 6H₂O?
Exam questions on Reactions of transition metal ions with bases and ligands
- A student has four separate solutions containing the hexaaqua ions of chromium(III), iron(III), cobalt(II) and copper(II). She adds aqueous sodium hydroxide dropwise to a sample of each solution and then adds an excess.Write the ionic equation for the formation of the precipitate when aqueous sodium hydroxide is added to the copper(II) solution, and state the colour of the precipitate.2 marks
- A student adds aqueous ammonia dropwise, and then in excess, to a pale blue solution of copper(II) sulfate containing [Cu(H₂O)₆]²⁺.Write the ionic equation for the ligand exchange reaction that forms the deep blue complex ion from [Cu(H₂O)₆]²⁺ and ammonia, and state the coordination number of copper before and after the reaction.2 marks
- Hexaaqua complexes of copper(II) and nickel(II) take part in ligand exchange reactions. Concentrated hydrochloric acid is added to a solution of [Cu(H₂O)₆]²⁺, and, separately, excess ethane-1,2-diamine (en), NH₂CH₂CH₂NH₂, is added to a solution of [Ni(H₂O)₆]²⁺.Write the equation for the reaction of [Cu(H₂O)₆]²⁺ with concentrated hydrochloric acid and state the colour change. Explain why the coordination number of copper changes.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).