JPJC 2026 H2 Chem Prelim Paper 4 QP

© Jurong Pioneer Junior College [Turn Over NAME CLASS JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2026 CHEMISTRY 9476/04 Higher 2 Paper 4 Practical 25 August 2026 2 hours 30 minutes Candidates answer on the Question paper. Additional Materials: As listed in the Confidential Instructions READ THESE INSTRUCTIONS FIRST Write your name, class and exam index number 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, 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 18, 19 and 20. Shift At the end of the examination, fasten all your work securely together. Laboratory The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 13 2 12 3 25 Total 50 This document consists of 20 printed pages and 2 blank pages.

2 © Jurong Pioneer Junior College 9476/04/J2 PRELIMINARY EXAM/2026 Answer all the questions in the spaces provided. 1 Inorganic and Organic Qualitative Analysis For Examiner’s Use (a) FA 1 and FA 2 are salts containing the same transition metal but in different oxidation states. You are provided with solutions of FA 1 and FA 2. You are also provided with Solution S , 1% starch solution (Keep for use in Question 2). You will perform tests to identify the transition metal contained in FA 1 and FA 2. (i) Perform the tests described in Table 1.1, and record your observations in the table. Unless otherwise stated, the volumes given below are approximate and should be estimated rather than measured. Test and identify any gases evolved. If there is no observable change, write no observable change. Table 1.1 tests observations 1 To 1 cm depth of FA 1 in a test-tube add 1 cm depth of dilute sulfuric acid, followed by 1 cm depth of aqueous potassium iodide. To the resulting mixture, add a few drops of Solution S. 2 To 1 cm depth of FA 2 in a test-tube add aqueous sodium hydroxide dropwise, with shaking, until in excess. Leave the mixture on standing for 2 minutes. To the resulting mixture, add 1 cm depth of hydrogen peroxide. [4] Commented [JPAA(1]: Added “in” for the phrase for use in Question 2 Commented [KYSJ(2]: To be fair and consistent with our teaching and QA notes, let’s add “ Leave the mixture on standing for 2 minutes. “ which is what we taught in TP4

3 © Jurong Pioneer Junior College 9476/04/J2 PRELIMINARY EXAM/2026 [Turn Over (ii) Explain the observations in Test 2 as fully as you can, with reference to the reactions occurring. Identify the transition metal ion present in FA2. For Examiner’s Use ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………... [3] (iii) State, with supporting evidence, the nature of FA 1. Nature of FA 1: ………………………………………….. Evidence: …………………………………………………………………………. ……………………………………………………………………………………... [2]

4 © Jurong Pioneer Junior College 9476/04/J2 PRELIMINARY EXAM/2026 (b) Before starting this analysis, ensure your Bunsen burner is turned off. You are provided with an organic liquid sample FA 3. The molecular formula of FA 3 is C3H6O2. You will perform tests to deduce the structure of FA 3. For Examiner’s Use (i) Perform the tests described in Table 1.2, and record your observations in Table 1.2. Observations in Test 4 have been recorded. Do not perform this test. Unless otherwise stated, the volumes given below are approximate and should be estimated rather than measured. If there is no observable change, write no observable change. Table 1.2 tests observations 1 To a 1 cm depth of FA 3 in a test-tube, add 2 cm depth of dilute sulfuric acid. Then add 2–3 drops of aqueous potassium manganate(VII). Warm the mixture in the hot water bath for two minutes. 2 Add 1 cm depth of aqueous silver nitrate to a test-tube. Then slowly add 1 cm depth of aqueous sodium hydroxide. Add aqueous ammonia slowly, with shaking, until the precipitate just dissolves. You may use a clean glass rod to stir the mixture and help dissolve the precipitate. Add 1 cm depth of FA 3 to this mixture and shake the tube. Warm the mixture in the hot water bath for two minutes. Important: After about 3 minutes, pour the mixture down the sink and wash out the test-tube several times with tap water. 3 To a 1 cm depth of FA 3 in a test-tube, add 10 drops of aqueous sodium hydroxide. Now add iodine solution dropwise, until a permanent yellow/orange colour is obtained. Warm the mixture in the hot water bath for two minutes. 4 To a 1 cm depth of FA 3 in a test-tube, cautiously add a small piece of sodium metal. Effervescence observed. H2 gas produced extinguishes a lighted splint with a “pop” sound. [3]

5 © Jurong Pioneer Junior College 9476/04/J2 PRELIMINARY EXAM/2026 [Turn Over (ii) The molecular formula of FA 3 is C3H6O2. Use the observations recorded in Table 1.2 to deduce a possible structure of FA 3. For Examiner’s Use [1] [Total: 13]

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7 © Jurong Pioneer Junior College 9476/04/J2 PRELIMINARY EXAM/2026 [Turn Over 2 Investigating the kinetics of the reaction between iodate(V) ions and hydrogensulfite ions For Examiner’s Use FA 4 is 0.100 mol dm–3 potassium iodate(V), KIO3. FA 5 is 0.0500 mol dm–3 sodium hydrogensulfite, NaHSO3. You are also provided with: • Solution S, 1% starch solution • deionised water • a waste beaker containing sodium carbonate solution Iodate(V) ions, IO3⁻(aq) react with hydrogensulfite ions, HSO3⁻(aq) as shown in equation 1 shown. equation 1 2IO3⁻(aq) + 5HSO3⁻(aq) → I2(aq) + 5SO42⁻(aq) + 3H+(aq) + H2O(l) In this experiment, the rate of the reaction is studied by measuring the rate of formation of iodine using a 'clock' method. You will vary the concentration of iodate(V) ions and measure the time taken for a fixed amount of iodine to be produced, which will be indicated by the formation of a blue-black colour in the presence of starch. The blue-black colour does not appear immediately because the iodine, I2(aq), produced can be reacted immediately with unreacted hydrogensulfite ions, HSO 3⁻(aq), in a competing reaction (fast) as shown in equation 2. equation 2 I2(aq) + HSO3⁻(aq) + H2O(l) → 2I⁻(aq) + SO42⁻(aq) + 3H+(aq) When all the hydrogensulfite has been consumed, any additional iodine that forms will turn the starch indicator blue-black. You will perform a series of five experiments. For each experiment, you will need to ensure that the same total volume of reaction mixture is used by adding deionised water as required. For each experiment, you will measure the time, t, for the blue-black colour to appear. You should avoid inhaling any gases produced. (a) In the space provided on page 8, prepare a table to record the following , to an appropriate level of precision: • all volumes of FA 4 (VFA 4), FA 5 (VFA 5) and deionised water (Vwater) used • all values of t, to the nearest second • calculated values of 1000 t to 3 significant figures Commented [JPAA(3]: Corrected the spelling error

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