CIE Nov 2015 v6 Paper 3 Q2

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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 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. Halfll the 250 cm3 beaker with water and heat it to about 80 C and then switch off the burner. This will be used as a water bath in (b). Keep two clean, dry test-tubes for use in (b). (a) FB 4 and FB 5 each contain two cations and one anion. One of the cations in FB 4 is the same as one of the cations in FB 5. The anion in FB 4 is the same as the anion in FB 5. (i) Separately dissolve about half of each of your samples of FB 4 and FB 5 in about 5 cm depth of distilled water in a boiling tube. Carry out the following tests and record your observations in the table. observations FB 4 FB 5 test To a 1 cm depth of solution in a test-tube, add a 1 cm depth of aqueous edta. To a 1 cm depth of solution in a test-tube, add a 1 cm depth of aqueous potassium iodide.UCLES 2015 9701/36/O/N/15<br /> PMT FB 4 observations FB 5 test To a 1 cm depth of solution in a test-tube, add aqueous sodium hydroxide. To a 1 cm depth of solution in a test-tube, add aqueous ammonia. To a 1 cm depth of solution in a test-tube, add a 1 cm depth of aqueous barium chloride or aqueous barium nitrate, then add dilute hydrochloric acid. (ii) From the observations identify three of the ions present in FB 4 and FB 5. The anion present in both FB 4 and FB 5 is. One cation present in FB 4 is. One cation present in FB 5 is. (iii) FB 4 and FB 5 each contain another cation from the list on page 11. This cation is the same in both FB 4 and FB 5. Carry out a test to identify this cation. Record details of the test and your observations.Identify the cation present in both FB 4 and FB 5. Cation is. [8]UCLES 2015 9701/36/O/N/15 [Turn over<br /> (b) FB 6 is an aqueous solution of an organic compound. 10 (i) Complete the table below. The observation with 2,4-dinitrophenylhydrazine has already been made. test observations PMT orange precipitate formed To a 1 cm depth of FB 6 in a test-tube, a few drops of 2,4-dinitrophenylhydrazine were added. To a 1 cm depth of FB 6 in a test-tube, add a 2 cm depth of dilute sulfuric acid. Place the test-tube in the water bath. Then add two or three drops of acidi ed aqueous potassium manganate(VII). To a 1 cm depth of aqueous silver nitrate in a test-tube, add a few drops of aqueous sodium hydroxide. Then add aqueous ammonia until the brown precipitate just dissolves. To this, add a 1 cm depth of FB 6. Place the test-tube in the water bath and leave to stand. Care: rinse the tube as soon as you have completed this test. (ii) What conclusion can you make about the identity of FB 6 from the observation of its reaction with 2,4-dinitrophenylhydrazine?(iii) What conclusion can you make about the identity of FB 6 from the observation of its reactions with acidi ed potassium manganate(VII) and silver nitrate in ammonia solution?(iv) What change in the oxidation state of silver occurs in the reaction between FB 6 and silver nitrate in ammonia solution? change fromto[5] [Total: 13]UCLES 2015 9701/36/O/N/15<br />

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