CIE Nov 2016 v3 Paper 4 Q1

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Answer all the questions in the spaces provided. PMT Copper is a transition element and has atomic number 29. (a) Complete the electronic configuration for the copper atom and the copper ion in the +2 oxidation state. copper atom [Ar]copper ion in the +2 oxidation state [Ar][2] (b) The following equilibrium exists between two complex ions of copper in the +2 oxidation state. [Cu(H2O)6]2+ + 4Cl[CuCl 4]2 + 6H2O (i) Name the type of reaction occurring here.[1] (ii) State the colours of these two complex ions. [Cu(H2O)6]2+[CuCl 4]2[1] (iii) State the shape of the [CuCl 4]2 ion.[1] (iv) Write the expression for the stability constant, Kstab, for this equilibrium. Kstab = [1] (c) Copper also forms the complex ions [Cu(NH3)2(H2O)4]2+ and [Cu(en)(H2O)4]2+ where en is the bidentate ligand ethane-1,2-diamine, H2NCH2CH2NH2. [Cu(H2O)6]2+ + 2NH3 [Cu(NH3)2(H2O)4]2+ + 2H2O [Cu(H2O)6]2+ + en [Cu(en)(H2O)4]2+ + 2H2O equilibrium 1 equilibrium 2 (i) What is meant by the term bidentate ligand?[2]UCLES 2016 9701/43/O/N/16<br /> PMT (ii) The table lists the values of stability constants for these two complexes. stability constant, Kstab [Cu(NH3)2(H2O)4]2+ [Cu(en)(H2O)4]2+ 7.94107 3.981010 What do these Kstab values tell us about the relative positions of equilibria 1 and 2?[1] (d) Nickel forms the complex ion [Ni(en)3]2+ in which it is surrounded octahedrally by six nitrogen atoms. (i) Name the type of stereoisomerism displayed by [Ni(en)3]2+.[1] (ii) Draw three-dimensional diagrams to show the two stereoisomers of [Ni(en)3]2+. [3] (e) Ethane-1,2-diamine is a useful reagent in organic chemistry. (i) Explain how the amino groups in ethane-1,2-diamine allow the molecule to act as a Brnsted-Lowry base.[2] (ii) Write an equation hydrochloric acid. for the reaction of ethane-1,2-diamine with an excess of[1]UCLES 2016 9701/43/O/N/16 [Turn over<br /> (f) (i) Under certain conditions, ethane-1,2-diamine reacts with ethanedioic acid, HO2CCO2H, to form the polymer Z. Draw the structure of this polymer, Z, showing two repeat units. PMT (ii) Name the type of reaction occurring during this polymerisation.[1] [2] (iii) Polymer Z is an example of a biodegradable polymer. Name a polymer that is non-biodegradable.[1] [Total: 20]UCLES 2016 9701/43/O/N/16<br />

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