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GCE MAY 2010 : (A2 3) Internal Assessment: Practical Examination1 - Revised

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Sp N ec e ifi w ca tio n Centre Number 71 Candidate Number ADVANCED General Certificate of Education 2010 Chemistry Internal Assessment Practical Examination 1 AC231 Assessment Unit A2 3 [AC231] THURSDAY 20 MAY TIME 2 hours 30 minutes. INSTRUCTIONS TO CANDIDATES Write your Centre Number and Candidate Number in the spaces provided at the top of this page. Answer all three questions. Write your answers in the spaces provided. INFORMATION FOR CANDIDATES The total mark for this paper is 70. Questions 1 and 2 are practical exercises each worth 25 marks. Question 3 is a planning exercise worth 20 marks. Quality of written communication will be assessed in Question 3. You may not have access to notes, textbooks and other material to assist you. A Periodic Table of elements (including some data) is provided. For Examiner s use only Question Number 1 2 3 110064 Total Marks 6032 Marks Modera -tion Mark 1 Titration exercise Teacher Examiner Remark Mark Check An acidified solution of potassium iodate(V) acts as an oxidising agent. You are provided with: a solution of potassium iodate(V) of unknown concentration; four 20 cm3 portions of sulphuric acid; four 1.5 g samples of potassium iodide; sodium thiosulphate solution of concentration 0.05 mol dm 3; starch indicator. Assuming that all the apparatus is clean and dry, you are required to carry out a titration and use your results to calculate the concentration of potassium iodate(V). (a) Give details of the procedure you intend to use. ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ______________________________________________________ [6] 6032 2 [Turn over (b) Carry out your procedure. Present your results in a suitable table and calculate the average titre. Teacher Examiner Remark Mark Check [10] 6032 3 [Turn over (c) Calculate the number of moles of iodine liberated in the conical flask. Teacher Examiner Remark Mark Check ________________________________________________________ ________________________________________________________ ________________________________________________________ ______________________________________________________ [2] (d) (i) Balance the following half-equation: IO3 + H+ I2 + H2O [2] (ii) Combine the reduction half-equation above with the following oxidation half-equation to produce a balanced redox equation: 2 I I2 + 2e __________________________________________________ [2] (e) Calculate the concentration of the potassium iodate(V) solution in g dm 3. ________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________ ______________________________________________________ [3] 6032 4 [Turn over BLANK PAGE (Questions continue overleaf) 6032 5 [Turn over 2 Observation/deduction Teacher Examiner Remark Mark Check Safety goggles must be worn at all times and care should be exercised during this practical examination. (a) You are provided with a salt, labelled A. Carry out the following tests. Record your observations in the spaces below. Test Observations 1 Describe the appearance of A. [1] 2 Dissolve a spatula measure of A in approximately 50 cm3 of water. [1] 3 Add a few drops of barium chloride solution to 2 cm3 of the solution of A. [1] 4 Add a few drops of sodium hydroxide solution to 2 cm3 of the solution of A. [2] 5 In a fume cupboard, add excess concentrated ammonia solution dropwise, until present in excess, to 2 cm3 of the solution of A. [3] 6 Add an equal volume of concentrated hydrochloric acid to 2 cm3 of the solution of A. [2] 6032 6 [Turn over Deduce the formula of the complex formed in Teacher Examiner Remark Mark Check Test 2 _______________________________________________ [1] Test 5 _______________________________________________ [1] Test 6 _______________________________________________ [1] Deduce the name of compound A. _____________________________________________________ [2] (b) Compounds B and C both have the molecular formula C3H6O. They both produce an orange solid when reacted with 2,4-dinitrophenylhydrazine. Carry out the following test on B. A sample of C is not required. Record your observations in the space below. Test Observations Mix 1cm3 of Fehling s No.1 solution with an equal volume of Fehling s No. 2 solution. Add about 1cm3 of B and heat in a water bath for at least five minutes. [3] Deduce the structural formula of B _____________________________________________________ [1] Deduce the structural formula of C _____________________________________________________ [1] 6032 7 [Turn over (c) Compounds D and E have the molecular formula C3H6O2. They both produce a triplet, quartet and singlet in their NMR spectra. Carry out the following test on D. A sample of E is not required. Record your observations in the space below. Test Teacher Examiner Remark Mark Check Observations Add a spatula measure of sodium carbonate to about 1cm3 of D in a test tube. [3] Deduce the structural formula of D _____________________________________________________ [1] Deduce the structural formula of E _____________________________________________________ [1] 6032 8 [Turn over BLANK PAGE (Questions continue overleaf) 6032 9 [Turn over Planning exercise 3 Teacher Examiner Remark Mark Check Preparation of Tin(IV) Iodide Tin(IV) iodide is a solid which can be prepared by reaction of excess tin with iodine by refluxing in a suitable solvent such as dichloromethane, CH2Cl2, which is toxic and flammable. You are required to prepare 6.0g of pure tin(IV) iodide based on the mass of iodine used. (a) Write an equation for the reaction. ______________________________________________________ [2] (b) Calculate the mass of iodine needed assuming a 90% yield. ________________________________________________________ ________________________________________________________ ________________________________________________________ ______________________________________________________ [4] (c) (i) State and explain relevant safety precautions apart from using safety glasses and a fume cupboard. ____________________________________________________ ____________________________________________________ ____________________________________________________ __________________________________________________ [2] (ii) Explain the term refluxing . ____________________________________________________ ____________________________________________________ __________________________________________________ [2] 6032 10 [Turn over (d) (i) How would you know when all the iodine has reacted? Teacher Examiner Remark Mark Check __________________________________________________ [2] (ii) How is the unreacted tin removed from the reaction mixture? _____________________________________________________ __________________________________________________ [1] (iii) How would you obtain crude tin(IV) iodide from the reaction mixture? _____________________________________________________ __________________________________________________ [2] (iv) How is crude tin(IV) iodide purified using the solvent? _____________________________________________________ _____________________________________________________ _____________________________________________________ _____________________________________________________ __________________________________________________ [3] Quality of written communication [2] THIS IS THE END OF THE QUESTION PAPER 6032 11 [Turn over Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright holders may have been unsuccessful and CCEA will be happy to rectify any omissions of acknowledgement in future if notified. 110064

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Additional Info : Gce Chemistry May 2010 Assessment Unit A2 3 Internal Assessment: Practical Examination 1
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