CIE Nov 2015 v3 Paper 4 Q4

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(a) (i) On the grid below, sketch the trend in the melting points of the Group IV elements. The point for germanium has already been shown. PMT melting point Si Ge Sn Pb [1] (ii) Suggest an explanation of this trend in terms of structure and bonding of the Group IV elements.[1] (b) GeO2, SnO2 and PbO2 are amphoteric oxides. (i) What is meant by the term amphoteric?[1] (ii) Construct an equation for the reaction of SnO2 with NaOH.[1] (c) (i) By quoting information from the Data Booklet explain why the reaction between Cr2O7 2(aq) ions and acidified Sn2+(aq) ions is feasible.[1]UCLES 2015 9701/43/O/N/15<br /> PMT (ii) Construct an equation for the reaction in (c)(i) and give any relevant observations. equationobservations[2] (d) (i) On heating, germanium(II) oxide disproportionates to form germanium(IV) oxide and germanium. Describe, using this reaction as an example, what is meant by a disproportionation reaction.[1] (ii) Some of the reactions of cyanogen, NCCN, are similar to those of chlorine, Cl Cl. On treatment with cold, aqueous sodium hydroxide, cyanogen disproportionates in a similar manner to chlorine. Complete the equation for this reaction. (CN)2 + NaOH++[1] (iii) Draw a dot-and-cross diagram for NCCN. Show the outer electrons only. [1]UCLES 2015 9701/43/O/N/15 [Turn over<br /> 10 (e) At room temperature, phosphorus atoms form P4 molecules rather than P2 molecules. The phosphorus molecule, P4, has a cage-like structure containing only PP single bonds. All the phosphorus atoms in P4 are trivalent. (i) Suggest a structure for P4. PMT [1] (ii) At a temperature of 1200 K P2 and P4 exist in equilibrium in the gas phase. P2 molecules contain the PP bond. The average bond energy of PP is 198 kJ mol1 while that of PP is 489 kJ mol1. Use the above bond energies to calculate the enthalpy change, H, for the following reaction. 2P2(g)P4(g) [2] (f) When phosphorus(V) chloride, PCl 5, is reacted with ammonium chloride, NH4Cl, hydrogen chloride gas, HCl, is released and a product with the molecular formula P3N3Cl 6 is formed. (i) Construct an equation for this reaction.[1] (ii) P3N3Cl 6 has a cyclic structure containing alternating phosphorus and nitrogen atoms in the ring system. All the nitrogen atoms are trivalent and all the phosphorus atoms are pentavalent. Suggest a structure for P3N3Cl 6.UCLES 2015 9701/43/O/N/15 [1] [Total: 15]<br /> 11 PMT TURN OVER FOR QUESTION 5.UCLES 2015 9701/43/O/N/15 [Turn over<br />

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