EJC 2026 Prelim H2 Chemistry Paper 4 QP

© EJC 9476/04/J2PRELIM/26 [Turn Over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examination 2026 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CIVICS GROUP 2 5 – INDEX NUMBER CHEMISTRY Paper 4 Practical 9476/04 20 August 2026 2 hour 30 minutes Candidates answer on the Question Paper Additional Materials: As listed in the Confidential Instructions READ THESE INSTRUCTIONS FIRST Write your name, civics group and registration number on 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 an HB pencil for any diagrams or graphs. Do not use paper clips, highlighters, 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. 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 /11 2 /12 3 /17 4 /10 Total /50 This document consists of 19 printed pages and 1 blank page.

2 © EJC 9476/04/J2PRELIM/26 Answer all the questions in the spaces provided. 1 Investigation of an organic compound and an inorganic compound FA 1 is an aqueous solution of an organic compound, Y, which contains two different functional groups. FA 2 contains two cations and one anion. You will perform tests to identify: • the functional groups in Y and hence deduce its possible structure • the ions present in FA 2. Unless otherwise stated, the volumes given in Table 1.1 and 1.2 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. (a) (i) Carry out the tests described in Table 1.1. Carefully record your observations at each stage of the tests in Table 1.1. Table 1.1 tests observations 1 To a 1 cm depth of dilute sulfuric acid in a test-tube, add 4 drops of potassium manganate (VII). Then add 1 cm depth of FA 1. Allow to stand in a hot water bath for two minutes, with occasional shaking. 2 Add 1 cm depth of FA 1 followed by equal volume of aqueous sodium hydroxide. Then slowly add 1 cm depth of iodine solution. Warm the mixture in the hot water bath if necessary. 3 To a 2 cm depth of FA 1 in a test-tube, add one spatula full of solid sodium carbonate. [3]

3 © EJC 9476/04/J2PRELIM/26 [Turn Over (ii) Y is a compound that has three carbon atoms and contains the elements carbon, hydrogen and oxygen only. Draw the structure of Y. Use your observations in Table 1.1. [1] (b) (i) Carry out the tests described in Table 1.2. Carefully record your observations at each stage of the tests in Table 1.2. Table 1.2 [4] (ii) Deduce the identity of the two cations in FA 2 using your results in (b)(i). ................................ ................................ ................................ ................................ ......... [2] (iii) Explain why it is difficult to identify the anion in FA 2 from the tests in (b)(i). ................................ ................................ ................................ ................................ ............. ................................ ................................ ................................ ................................ ............. ................................ ................................ ................................ ................................ ......... [1] [Total: 11] tests observations 4 Add 1 cm depth of FA 2 to a clean boiling tube. Add sodium hydroxide until there is no further change. Warm the mixture. 5 Add 1 cm depth of FA 2 to a clean test - tube. Add aqueous ammonia until there is no further change. 6 Add 1 cm depth of FA 2 to a clean test - tube. Add 5 drops of aqueous silver nitrate. Add aqueous ammonia to the mixture, with shaking, until the aqueous ammonia is in excess.

4 © EJC 9476/04/J2PRELIM/26 2 Investigating the kinetics of the reaction between iron(III) ions and iodide ions FA 3 is 0.0500 mol dm−3 potassium iodide, KI. FA 4 is 0.00500 mol dm−3 sodium thiosulfate, Na2S2O3. FA 5 is 0.0500 mol dm−3 aqueous iron(III) chloride, FeCl3. You are also provided with a starch indicator. Iron(III) ions, Fe3+, can oxidise iodide ions, I– to iodine, I2 as shown in equation 1. equation 1 2Fe3+(aq) + 2I−(aq) → 2Fe2+(aq) + I2(aq) The initial rate of th e reaction can be approximated by adding a small, fixed amount of thiosulfate ions, S2O 2– 3 . As the iodine is produced, it reacts immediately with the thiosulfate ions and is reduced back to iodide ions as shown in equation 2. equation 2 I2(aq) + 2S2O 2– 3 (aq) → S4O 2– 6 (aq) + 2I−(aq) Once all thiosulfate ions have reacted, the concentration of iodine rapidly increases . The presence of starch in the reaction mixture leads to the formation of a dark blue coloration, indicating the formation of an iodine-starch complex. In this experiment, the rate of the reaction is studied by measuring the time taken for the mixture to turn blue-black. You will perform a series of five experiments. Then, you will graphically analyse your results to determine the order with respect to the concentration of iron(III) ions, [Fe3+ For each experiment, you will vary the volume of FA 5 added, VFA 5, and measure the time taken, t, for the dark blue colour to first ap pear. The total volumes of the reaction mixture must be kept the same as that used in experiment 1, by adding deionised water as required. Prepare a table in the space provided on page 6 in which to record , to an appropriate degree of precision for each experiment: • the volumes of FA 5 (VFA 5), and deionised water • all values of t • calculated values of log(1/t) • calculated values of log(VFA 5).

5 © EJC 9476/04/J2PRELIM/26 [Turn Over (a) Experiment 1 step 1 Use a 25 cm3 measuring cylinder to measure the following into a 100 cm3 conical flask: • 10.0 cm3 of FA 3 • 20.0 cm3 of FA 4 • 10.0 cm3 of starch step 2 Swirl the contents of the conical flask gently to ensure mixing. step 3 Use the measuring cylinder labelled FA 5 to transfer 20.0 cm 3 of FA 5 to the conical flask. Start the stopwatch when about half of the FA 5 solution has been added. Ignore any initial colouration on mixing. step 4 Mix the contents thoroughly by swirling the flask several times before leaving the flask to stand on a white tile. step 5 Stop the stopwatch when the solution first turns blue-black. step 6 Record the time taken, t, to the nearest second, in your table. step 7 Wash the flask thoroughly with tap water and then deionised water. Stand the flask upside down on a paper towel to drain. Experiment 2 Repeat experiment 1, but add both 5.0 cm 3 of FA 5 and 15.0 cm 3 of deionised water to the measuring cylinder labelled FA 5 in step 3 before transferring into the conical flask. Experiment 3 to 5 Repeat the experiment another three times with different volumes of FA 5. The volume of FA 5 chosen should be between 5.0 cm3 and 20.0 cm3. In each experiment, you should add deionised water to the measuring cylinder labelled FA 5 in step 3 to ensure the same total volume of reaction mixture is used. You should alternate the use of the two 100 cm3 conical flasks. Record all required volumes, time taken and calculated values in your table.

6 © EJC 9476/04/J2PRELIM/26 Results [5]

7 © EJC 9476/04/J2PRELIM/26 [Turn Over (b) (i) Plot a graph of log(1/t)