CIE Jun 2014 v2 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 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.UCLES 2014 9701/32/M/J/14<br /> (a) Water in rivers and streams contains a range of different cations and anions. A particular salt occurs in some samples of spring water. You will carry out tests to identify this salt. PMT FB 4 is a solution of the salt. It contains one cation, which is listed in the Qualitative Analysis Notes on page 10. It also contains one anion, which is either sulfate, SO4 2, or sul te, SO3 2. (i) Choose reagents that will allow you to identify the cation in FB 4. Carry out suitable tests using these reagents and record your observations in the space below. The cation in FB 4 is. (ii) Choose reagents to identify the anion in FB 4. Carry out suitable tests using these reagents and record your results in the space below. II III IV VI VII VIII [8] The anion in FB 4 is.UCLES 2014 9701/32/M/J/14 [Turn over<br /> Before starting parts (b) and (c), half- ll a 250 cm3 beaker with water and heat with a Bunsen burner to approximately 60 C. You will use this as a hot water bath. Turn off the Bunsen burner. PMT (b) FB 5, FB 6 and FB 7 are solutions each containing a single compound which could be ethanol, ethanal or propanone. To identify each compound you will react the samples with Tollens' reagent and with acidi ed potassium manganate(VII). (i) Preparation of Tollens' reagent To approximately 2 cm depth of aqueous silver nitrate in a boiling tube, add approximately 0.5 cm depth of aqueous sodium hydroxide. Add aqueous ammonia a little at a time with continuous shaking until the brown precipitate just dissolves. Do not add an excess of ammonia. test FB 5 observations FB 6 FB 7 To a 1 cm depth of each solution in a clean, dry test-tube add a few drops of the Tollens reagent that you have prepared. Do not shake the tube. If no reaction is seen, warm the tube in the hot water bath. When you have made your observations, rinse out all the test-tubes and the boiling tube which were used with Tollens reagent. To a 1 cm depth of each solution in a test-tube add a 1 cm depth of dilute sulfuric acid. Then add a few drops of aqueous potassium manganate(VII). If no reaction is seen, warm the tube in the hot water bath. Do not carry out this test (ii) Identify each compound. FBcontains ethanol. FBcontains ethanal. FBcontains propanone. II III IVUCLES 2014 9701/32/M/J/14<br /> PMT (iii) Another reagent can be used with these samples to identify which compounds have a carbonyl group, C=O. This reagent has not been supplied so you cannot carry out this test. State the reagent and the expected observations of the three tests. reagent:expected observations FB 5FB 6FB 7[7] (c) FB 8 is an aqueous solution of an organic compound. Carry out the following tests. You do not need to identify FB 8. test observations To a 1 cm depth of FB 8 in a test-tube add a 1 cm depth of dilute sulfuric acid. Then add a few drops of aqueous potassium manganate(VII). If no reaction is seen, place the test-tube in the hot water bath and leave to stand. To a 1 cm depth of FB 8 in a test-tube carefully add a small spatula measure of sodium hydrogen carbonate. [3] [Total: 18]UCLES 2014 9701/32/M/J/14 [Turn over<br />

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