CIE Jun 2016 v2 Paper 4 Q10

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PMT 10 (a) (i) Complete the electronic configuration of the iron atom. 19 Fe 1s22s22p6 [1] (ii) In some of its complexes, the Fe3+ ion has only one unpaired electron in its d orbitals. Using the symbolsandto represent electrons of opposite spins, complete the following diagram to show the d orbital electronic configuration of this Fe3+ ion.3d energy[1] (b) A solution containing a mixture of Sn2+(aq) and Sn4+(aq) is added to a solution containing a mixture of Fe2+(aq) and Fe3+(aq). Use E o data from the Data Booklet to predict the reaction that might take place when the two solutions are mixed, and write an equation for the reaction.[2]UCLES 2016 9701/42/M/J/16 [Turn over<br /> PMT 20 (c) Hexaaquairon(III) ions are pale violet. They form a colourless complex with fluoride ions, F, equilibrium 1, and a deep-red complex with thiocyanate ions, SCN, equilibrium 2. [Fe(H2O)6]3+ + F violet [Fe(H2O)5F]2+ + H2O colourless equilibrium 1 Kstab = 2.0105 mol1 dm3 [Fe(H2O)6]3+ + SCN violet [Fe(H2O)5SCN]2+ + H2O deep-red equilibrium 2 Kstab = 1.0103 mol1 dm3 (i) Predict and explain the sequence of colour changes you would observe in each of the following experiments. A few drops of KSCN(aq) are added to 5 cm3 of Fe3+(aq), followed by a few drops of KF(aq).A few drops of KF(aq) are added to 5 cm3 of Fe3+(aq), followed by a few drops of KSCN(aq).[4] (ii) What type of reaction is occurring during the experiments in (i)?[1] [Total: 9] Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.UCLES 2016 9701/42/M/J/16<br />

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