CIE Nov 2016 v6 Paper 3 Q3

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PMT 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 identified by a test, described in the appropriate place in your observations. You should indicate clearly at what stage in a test a change occurs. 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) FB 4 and FB 5 are aqueous solutions of equal concentrations, in mol dm3. Each contains one anion and one cation. The cation is the same in both FB 4 and FB 5. Half fill the 250 cm3 beaker with water. Heat the water to about 80 C and then turn off the Bunsen burner. This is the hot water bath needed in the tests below. To about a 2 cm depth of aqueous silver nitrate in a test-tube, add a few drops of aqueous sodium hydroxide to give a grey / brown precipitate. Then add aqueous ammonia dropwise until the precipitate just disappears. This solution is Tollens reagent and is needed in a test below. (i) Carry out the tests on separate samples of FB 4 and FB 5 and complete the table. observations FB 4 FB 5 test To a 1 cm depth of solution in a test-tube in a test-tube rack, add a spatula measure of sodium carbonate. To a 1 cm depth of solution in a test-tube, add a few drops of acidified potassium manganate(VII). Place the test-tube in the hot water bath. To a 1 cm depth of Tollens reagent in a test-tube, add a few drops of solution. Place the test-tube in the hot water bath and leave for several minutes.UCLES 2016 9701/36/O/N/16 [Turn over<br /> PMT (ii) From your observations in (i), identify the cation present in both FB 4 and FB 5. cation(iii) From your observations in (i), what can be deduced about the anion present in FB 4?(iv) Place a 1 cm depth of FB 4 and FB 5 separately in two test-tubes. Measure and record the temperature of the two solutions. FB 4C FB 5C To each solution, add an approximately 2 cm length of magnesium ribbon. Measure and record the maximum temperature reached in each test-tube. FB 4 + MgC FB 5 + MgC (v) Explain why there is a difference in the temperature rise for the reactions of magnesium with solutions FB 4 and FB 5.[8]UCLES 2016 9701/36/O/N/16<br /> (b) FB 6 is a solid that contains two cations from those listed on page 10. You are to plan a series of experiments that will enable you to identify the cations present. You should then carry out your plan, record all the observations you made in a suitable table and identify the cations present. PMT cations present areand[5] [Total: 13]UCLES 2016 9701/36/O/N/16 [Turn over<br />

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