CIE Mar 2017 v2 Paper 4 Q6

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(a) (i) Draw the shape of one of the d orbitals. 12 (ii) Complete the following electronic configurations. Ni 1s22s22p63s23p6Ni3+ 1s22s22p63s23p6PMT [1] [1] (b) (i) Complete the diagram to show how the presence of ligands around an isolated transition metal ion affects the energy of the d orbitals. energy degenerate d orbitals octahedral complex isolated transition metal ion tetrahedral complex [1] (ii) Explain why transition metal complexes are coloured.[2] (iii) [Cu(H2O)6]2+ is pale blue but [Cu(NH3)4(H2O)2]2+ is deep purple-blue. Suggest a reason for this.[1]UCLES 2017 9701/42/F/M/17<br /> (c) The diagram shows the visible spectrum of a solution of [V(H2O)6]3+. 13 PMT absorption blue green red 350 400 450 500 550 600 650 700 wavelength / nm State and explain what colour the solution is. colour of solutionexplanation[2] (d) (i) In the presence of chloride ions, [V(H2O)6]3+ reacts to form a mixture of isomeric octahedral complexes. [V(H2O)6]3+ + 2Cl[V(H2O)4Cl 2]+ + 2H2O Complete the three-dimensional diagrams to show the two isomers of [V(H2O)4Cl 2]+. isomer 1 isomer 2 [2] (ii) State the type of isomerism shown by isomer 1 and isomer 2 in (i).[1]UCLES 2017 9701/42/F/M/17 [Turn over<br /> PMT (e) (i) The complex [V(H2O)6]3+ also reacts with ethane-1,2-diamine (en), H2NCH2CH2NH2, to form a mixture of isomeric octahedral complexes. 14 [V(H2O)6]3+ + 3en [V(en)3]3+ + 6H2O Complete the three-dimensional diagrams to show the two isomers of [V(en)3]3+. You may use N N to represent en. isomer 1 isomer 2 [2] (ii) State the type of isomerism shown by isomer 1 and isomer 2 in (i).[1]UCLES 2017 9701/42/F/M/17<br /> 15 (f) The reaction of [Ni(H2O)6]2+ with aqueous ammonia produces the complex [Ni(NH3)6]2+. [Ni(H2O)6]2+(aq) + 6NH3(aq) [Ni(NH3)6]2+(aq) + 6H2O(l) (i) Write the expression for Kstab for [Ni(NH3)6]2+. Kstab = PMT [1] (ii) [Ni(H2O)6]2+ also reacts with en to form [Ni(en)3]2+. The values of the stability constants for the two complexes are shown. Kstab [Ni(NH3)6]2+ = 4.8107 mol6 dm18 Kstab [Ni(en)3]2+ = 2.01018 mol3 dm9 A solution containing equal numbers of moles of ammonia and en is added to [Ni(H2O)6]2+. State which complex is produced in the larger amount. Explain your answer.[1] (iii) Adding a limited amount of en to [Ni(H2O)6]2+ forms the complex [Ni(H2O)2(en)2]2+. Suggest the number of possible stereoisomers of [Ni(H2O)2(en)2]2+. Explain your answer. You are advised to include three-dimensional diagrams in your answer.[2]UCLES 2017 9701/42/F/M/17 [Total: 18] [Turn over<br />

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