CIE Jun 2015 v1 Paper 3 Q3

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Qualitative Analysis At each stage of any test you are to record details of the following.colour changes seen the formation of any precipitate the solubility of such precipitates in an excess of the reagent added Where gases are released they should be identi ed by a test, described in the appropriate place in your observations. You should indicate clearly at what stage in a test a change occurs. Marks are not given for chemical equations. No additional tests for ions present should be attempted. If any solution is warmed, a boiling tube MUST be used. Rinse and reuse test-tubes and boiling tubes where possible. Where reagents are selected for use in a test, the name or correct formula of the element or compound must be given. (a) In Question 1 you used FA 2. This solution was prepared from hydrated ammonium iron(II) sulfate, (NH4)2Fe(SO4)2.6H2O. To a 1 cm depth of FA 2 in a test-tube, add a small spatula measure of sodium carbonate. Record your observations. Solutions containing Fe2+ ions can quickly be oxidised in air if they are prepared by dissolving the solid in distilled water. Use your observations to suggest what other substance was added to solid (NH4)2Fe(SO4)2.6H2O to prepare FA 2.[2]UCLES 2015 9701/31/M/J/15 [Turn over<br /> (b) FA 6 is a mixture of two salts, each of which contains a single cation and a single anion from those listed in the Qualitative Analysis Notes on pages 10 and 11. Do the following tests and record your observations in the table below. test observations (i) Place a small spatula measure of FA 6 in a hard-glass test-tube and heat strongly. (ii) Place a small spatula measure of FA 6 in a test-tube and carefully add dilute sulfuric acid until the reaction is complete, then add aqueous sodium hydroxide. (iii) To a 3 cm depth of distilled water in a boiling tube, add the remaining sample of FA 6. Stir and thenlter the mixture into a clean boiling tube. You will use this solution for tests (iv)(vi). (iv) To a 1 cm depth of the solution from (iii) in a test-tube, add aqueous sodium hydroxide. (v) To a 1 cm depth of the solution from (iii) in a test-tube, add aqueous ammonia. (vi) To a 1 cm depth of the solution from (iii) in a test-tube, add aqueous barium chloride or aqueous barium nitrate.UCLES 2015 9701/31/M/J/15<br /> (vii) Suggest possible identities for the ions present in FA 6. cationsanions(viii) Describe a further test that would allow you to determine exactly which anions are present. Explain your choice. Do not do this test.[11] [Total: 13]UCLES 2015 9701/31/M/J/15<br />

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