2023 VJC H2 Prelim P4 QP

This document consists of 18 printed pages and 2 blank pages. © VJC 2023 9729/04/PRELIM/23 [Turn over CANDIDATE NAME CT GROUP VICTORIA JUNIOR COLLEGE PRELIMINARY EXAMINATION Higher 2 ……………………………………………….………….. …………………………….. CHEMISTRY 9729/04 Paper 4 Practical Candidates answer on the Question Paper. 24 Aug 2023 2 hours 30 minutes Additional Materials: As listed in the instructions below READ THESE INSTRUCTIONS FIRST Write your name and CT group on all the work you hand in. Give details of the practical shift and laboratory where appropriate, in the boxes provided. Write in dark blue or black pen. You may use a HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. Qualitative Analysis Notes are printed on pages 17 and 18. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. Shift Laboratory For Examiner’s Use 1 2 3 4 Total / 55

2 © VJC 2023 9729/04/PRELIM/23 Answer all the questions in the spaces provided. 1 Inorganic and organic qualitative analysis In this question, you will carry out tests on two solutions, FA 1 and FA 3 , and make conclusions about them. Unless otherwise stated, the volumes given below are approximate and should be estimated rather than measured. Test and identity any gases evolved. If there is no observable change, write no observable change. (a) (i) FA 1 is an aqueous solution that contains two cations and one anion listed in the Qualitative Analysis notes. You will carry out the tests in Table 1.1, which will allow you to identify the two cations present in FA 1. Table 1.1 tests observations 1 Test the FA 1 solution using Universal Indicator paper. Using the colour chart provided, record the pH of the solution. 2 To 1 cm depth of FA 1 , add 1 cm depth of KI. Let the solution stand for 1 min and observe any colour change that occurs. To the resulting solution, add 5 drops of starch solution. 3 To 2 cm depth of FA 1, add aqueous ammonia dropwise with shaking till 4 cm depth of aqueous ammonia has been added. Swirl and filter the mixture, collecting the filtrate in a clean test -tube. The filtrate is FA 2 which should be put to one side for use in Test 4.

3 © VJC 2023 9729/04/PRELIM/23 [Turn over 4 To 1 cm depth of FA 2, carefully add nitric acid dropwise until no further change is seen. [3] (ii) Identify the two cations in FA 1 and state the evidence for each cation by completing Table 1.2. Table 1.2 [2] cations evidence (iii) With the aid of a balanced equation, explain your observation in Test 1 of Table 1.1 above. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (iv) One of the cations present in FA 1 reacts with the KI solution added in Test 2 of Table 1.1 above. Suggest a balanced equation to represent this reaction. ............................................................................................................................... [1]

4 © VJC 2023 9729/04/PRELIM/23 (v) Only one anion is present in FA 1. The anion is not carbonate or sulfite and does not contain any nitrogen. Describe and carry out a series of tests that will allow you to identify the anion. Before carrying out the tests, you are required to dilute the given FA 1 solution by adding 1 cm depth of FA 1 solution to a clean test -tube, followed by adding deionised water until the test-tube is half full. Use the diluted solution to carry out your proposed tests. [2] (vi) Use your results in (a)(v) to identity the anion present in FA 1. Anion present: ............................. [1]

5 © VJC 2023 9729/04/PRELIM/23 [Turn over (b) (i) FA 3 is an aqueous solution containing an organic compound with only one functional group present. Perform Test 1 in Table 1. 3. There is no need to perform Test 2 as the observation has been completed for you. Table 1.3 tests observations 1 Add about 1 cm depth of FA 3 in a test-tube. To this test -tube, add 6 drops of sodium hydroxide solution, followed by adding iodine solution, dropwise, until a permanent orange/red colour is present. Half fill a 250 cm 3 beaker with warm water. Immerse the test-tube into the warm water for two minutes. 2 Add about 1 cm depth of FA 3 in a test–tube. To this test –tube, add 2 drops of potassium dichromate ( VI), followed by 1 cm depth of dilute sulfuric acid. Half fill a 250 cm 3 beaker with warm water. Immerse the test -tube into the warm water for two minutes. No observable change [1] (ii) State the functional group present in FA 3 and support your answer with evidence from Table 1.3. functional group evidence [2] [Total: 14]

6 © VJC 2023 9729/04/PRELIM/23 2 Determination of the value for the number of water of crystallisation, n, in an iron(II) salt, FeSO4•nH2O FA 4 is hydrated iron(II) sulfate, FeSO4•nH2O. FA 5 is 1.00 mol dm−3 dilute sulfuric acid, H2SO4. FA 6 is 0.0100 mol dm−3 potassium manganate(VII), KMnO4. You are to carry out titration to determine the number of water of crystallisation, n, in FA 4, which is the hydrated iron(II) sulfate, FeSO4•nH2O. This involves preparing a standard solution FA 7 by dissolving a fixed mass of FA 4 in dilute sulfuric acid, FA 5 with the use of a volumetric flask. FA 6 is then titrated with FA 7. The two half–equations for the titration are as follows: MnO4− + 8H+ + 5e− → Mn2+ + 4H2O Fe2+ → Fe3+ + e− (a) Procedure 1. Weigh the capped container containing solid FA 4. Record the mass in your table in the space provided on Page 6. 2. Transfer all the solid FA 4 into a 150 cm3 beaker. 3. Reweigh the empty capped container. Record this mass in your table on Page 7. 4. Using a 50 cm3 measuring cylinder, add 50.0 cm3 of FA 5 to dissolve the solid FA 4 in the beaker. Stir carefully and allow time for the entire amount of solid to dissolve. 5. Quantitatively transfer the resultant solution in the