Edexcel Jun 2011 Paper 6 Q1 (with explained solutions) |

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Edexcel Jun 2011 Paper 6 Q1

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PMT Answer ALL the questions. Write your answers in the spaces provided. 1 Solid W is a blue salt containing a transition metal complex cation and one anion. (a) Give the formulae of two different transition metal ions which can form blue complex cations. (2)(b) Complete the following table. (i) (ii) Test Heat compound W. Observation Inference(s)Water Test any gas evolved with moist red litmus paper. Red litmus paper turns blue(iii) Suggest two sources of the water which was given off when a pure dry sample of W was heated. (1) (1) (2)(c) The following tests are carried out on separate portions of an aqueous solution of W. Complete the table. Note: in the third column, the formula of the ion, molecule or compound giving rise to the observation is required. (i) (ii) (iii) Test Add concentrated hydrochloric acid slowly, Observation Formula-coloured precipitate Cu(OH)2 green-yellow solution until in excess. Acidify with dilute hydrochloric acid and then add barium chloride solution. Add dilute sulfuric acid until the solution is pale blue; then add potassium iodide solution. white precipitate white precipitatein a brown solution*P38481A0212* (1) (1) (1) (1) (1)<br />
(d) Suggest the formula of the complex cation in an aqueous solution of compound W. (1)(Total for Question 1 = 12 marks) PMT *P38481A0312* Turn over<br />

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Question Number 1 (a) Question Number 1 (b)(i) Question Number 1 (b)(ii) Question Number 1 (b)(iii) Question Number 1 (c)(i) Question Number 1 (c)(ii) Acceptable Answers Two of Cu2+,Cr2+, Co2+, Ni2+ (2) ALLOW [Cr(H2O)6]2+ ; [Cu(H2O)6]2+ ; [Cu(H2O)4]2+, [Cu(NH3)4]2+, [Cu(H2O)2(NH3)4]2+ [Ni(NH3)6]2+, [Ni(NH3)4]2+, [Co(H2O)6]2+ any other blue complex ion e.g. VO2+. If two correct names are given award (1) Two different ammines (different number of ammonia ligands) of the same metal ion (1) only Ignore any names Acceptable Answers Steam / water vapour / colourless liquid on (cool parts of) test tube Acceptable Answers Ammonia / contains ammonium (ion)/ammonium salt/ammonia ligand/ethylenediamine (ligand) ALLOW correct formulae Reject Any blue compound containing these ions. Mark Reject Any test for water vapour, e.g. CoCl2 Reject Mark Mark Acceptable Answers Reject Mark Water evolved could come from hydration / water of crystallization (1) or from ligand water (1) which could be shown in a formula The crystals are damp Acceptable Answers Reject (Any) blue (1) 2 / CuCl3 CuCl4(1) Acceptable Answers BaSO4 CuCl2; names Reject Barium sulphate, SO4 2Mark Mark 6CH08/01 1106<br />
Question Number 1 (c)(iii) Question Number 1 (d) Acceptable Answers CuI / Cu2I2 (1) I2 / I3 If names correctly given allow (1)(1) Reject Copper(I) iodide, CuI2 Iodine Acceptable Answers Reject [Cu(NH3)x(H2O)6-x]2+, x = 14 ALLOW the following: x = 5 or 6 [Cu(NH3)4]2+ [Cu(H2O)2(NH3)4]2+[SO4 charges must be present 2 ] but both [Cu(H2O)2(NH3)4]SO4 Mark Mark 6CH08/01 1106<br />

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