(a) Copper shows typical properties of transition elements, including its behaviour as a catalyst. Complete Table 5.1 to show the total number of unpaired electrons in the 3d and 4s orbitals of an isolated gaseous Cu atom and a Cu2+ ion. [Table 5.1] [1] (b) The 3d orbitals in an isolated Cu2+ ion are degenerate. Complete the diagram to show the relative energies of the 3d orbitals in an isolated Cu2+ ion and in Cu2+ in a tetrahedral complex. [diagram] [2] (c) Explain why transition elements behave as catalysts. [2] (d) CN⁻ is a monodentate ligand. Table 5.2 shows information about two complex ions that contain only CN⁻ ions as ligands. Complete Table 5.2. [Table 5.2] [2] (e) The complex ion [Au(CN)2Br2]⁻ displays geometrical (cis/trans) isomerism. Draw the structure of trans-[Au(CN)2Br2]⁻. State its shape and the Br-Au-Br bond angle. shape Br-Au-Br bond angle = [2] (f) An impure sample of a vanadium(V) compound of mass 0.250 g is dissolved in aqueous acid. This solution contains VO3⁻ ions. An excess of zinc is added to this solution. All the VO3⁻ ions are reduced to V2+ ions and Zn atoms are oxidised to Zn2+ ions. The unreacted zinc is removed and the resulting solution is titrated with acidified MnO4⁻. The end-point is reached when 22.5 cm³ of 0.0750 mol dm⁻³ MnO4⁻ is added. A redox reaction takes place and all the V2+ reacts forming VO3⁻. 3MnO4⁻ + 5V2+ + 3H2O → 3Mn2+ + 5VO3⁻ + 6H+ (i) Calculate the percentage by mass of vanadium in the 0.250 g of impure sample. Assume the impurities do not contain any vanadium ions. Show your working. percentage of vanadium = [3] (ii) Complete the equation for the reaction between acidified VO3⁻ ions and Zn metal. ...... VO3⁻ + ...... Zn + ...... → ...... V²⁺ + ...... Zn²⁺ + ...... [2]

1. (a)Complete Table 5.1 to show the total number of unpaired electrons in the 3d and 4s orbitals of an isolated gaseous Cu atom and a Cu2+ ion. [Table 5.1][1]
2. (b)The 3d orbitals in an isolated Cu2+ ion are degenerate. Complete the diagram to show the relative energies of the 3d orbitals in an isolated Cu2+ ion and in Cu2+ in a tetrahedral complex. [diagram][2]
3. (c)Explain why transition elements behave as catalysts.[2]
4. (d)CN⁻ is a monodentate ligand. Table 5.2 shows information about two complex ions that contain only CN⁻ ions as ligands. Complete Table 5.2. [Table 5.2][2]
5. (e)The complex ion [Au(CN)2Br2]⁻ displays geometrical (cis/trans) isomerism. Draw the structure of trans-[Au(CN)2Br2]⁻. State its shape and the Br-Au-Br bond angle. shape Br-Au-Br bond angle =[2]
6. (f)(i)An impure sample of a vanadium(V) compound of mass 0.250 g is dissolved in aqueous acid. This solution contains VO3⁻ ions. An excess of zinc is added to this solution. All the VO3⁻ ions are reduced to V2+ ions and Zn atoms are oxidised to Zn2+ ions. The unreacted zinc is removed and the resulting solution is titrated with acidified MnO4⁻. The end-point is reached when 22.5 cm³ of 0.0750 mol dm⁻³ MnO4⁻ is added. A redox reaction takes place and all the V2+ reacts forming VO3⁻. 3MnO4⁻ + 5V2+ + 3H2O → 3Mn2+ + 5VO3⁻ + 6H+ Calculate the percentage by mass of vanadium in the 0.250 g of impure sample. Assume the impurities do not contain any vanadium ions. Show your working. percentage of vanadium =[3]
7. (f)(ii)Complete the equation for the reaction between acidified VO3⁻ ions and Zn metal. ...... VO3⁻ + ...... Zn + ...... → ...... V²⁺ + ...... Zn²⁺ + ......[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.