Complete the electronic configuration of the copper(II) ion. 1s²2s²2p⁶

1. (a)(i)Complete the electronic configuration of the copper(II) ion. 1s²2s²2p⁶[1]
2. (a)(ii)State the colour of the solutions containing the following ions. • [Cu(H₂O)₆]²⁺(aq) • [CuCl₄]²⁻(aq)[1]
3. (a)(iii)Octahedral complexes of Cu²⁺ with different ligands can have different colours. Explain why.[2]
4. (b)Copper(I) and silver(I) salts are colourless. Suggest why.[2]
5. (c)(i)Consider the following two equilibria and associated data values at 298 K. AgBr(s) ⇌ Ag⁺(aq) + Br⁻(aq) equilibrium 1 Ksp = 5.0 × 10⁻¹³ mol² dm⁻⁶ Ag⁺(aq) + 2NH₃(aq) ⇌ [Ag(NH₃)₂]⁺(aq) equilibrium 2 Kstab = 1.7 x 10⁷ mol⁻² dm⁶ The equilibrium constant for equilibrium 1 is the solubility product, Ksp, of AgBr(s). The equilibrium constant for equilibrium 2 is the stability constant, Kstab, for the formation of [Ag(NH₃)₂]⁺(aq). Calculate the solubility of AgBr at 298 K in mol dm⁻³. solubility of AgBr =[1]
6. (c)(ii)Use Le Chatelier's principle as applied to equilibria 1 and 2 to suggest why AgBr(s) dissolves in concentrated NH₃(aq).[2]
7. (c)(iii)Use equilibria 1 and 2 to construct an equation for the reaction of AgBr(s) with concentrated NH₃(aq). This is equilibrium 3. equilibrium 3[1]
8. (c)(iv)Write an expression for the equilibrium constant of equilibrium 3, Keq3, in terms of Ksp for equilibrium 1 and Kstab for equilibrium 2. Keq3 =[1]
9. (d)Define the term standard electrode potential, Eᵒ.[1]
10. (e)(i)Complete and label the diagram to show how the standard electrode potential, Eᵒ, of Ag⁺(aq)/Ag(s) could be measured under standard conditions. [Figure X.X][4]
11. (e)(ii)Use the Data Booklet to label the diagram in (e)(i) to show: • which is the positive electrode, • the direction of electron flow in the external circuit when a current flows.[1]

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