RI 2026 H2 Chem Prelims P4 QP

© Raffles Institution 2026 9476/04/A/26 [Turn Over CANDIDATE NAME ( ) CLASS 26S0 RAFFLES INSTITUTION 2026 YEAR 6 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY Paper 4 Practical 9476/04 26 August 2026 2 hours 30 minutes Do NOT turn over the Question Booklet until you are told to do so. READ THESE INSTRUCTIONS FIRST. Write your name and class on the space provided when instructed to do so. Give details of the practical shift and laboratory where appropriate, in the space 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 number of marks is given in brackets [ ] at the end of each question or part question. 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 22, 23 and 24. Shift Laboratory Bench Number For Examiner’s Use Question Marks 1 / 18 2 / 10 3 / 12 4 / 10 Total / 50 This document has 24 pages. Any blank pages are indicated.

2 © Raffles Institution 2026 9476/04/A/26 [Turn Over Answer all questions in the space provided. 1 Determination of the equilibrium constant for the hydrolysis of an ester Compound W is an ester with the formula CH3COOR. W undergoes hydrolysis catalysed by acid as shown in reaction 1 below. W You are to perform an experiment to determine the equilibrium constant, K1, for the hydrolysis of W. An aqueous solution of W was mixed with dilute HC l. Immediately after mixing, the concentration of W was 0.0600 mol dm −3 and the concentration of HC l was 0.0300 mol dm −3. The mixture was left in the laboratory for 1 week to allow it to reach equilibrium. The resultant mixture is labelled FA 1. The total amount of CH3COOH and HC l in FA 1 can be determined by titrating against a standard solution of sodium hydroxide. FA 2 is 0.100 mol dm−3 sodium hydroxide solution. Solution T is thymolphthalein indicator. (a) (i) Titration of FA 1 against FA 2 1. Fill a burette with FA 2. 2. Pipette 25.0 cm3 of FA 1 into a 250 cm3 conical flask. 3. Add about 6 drops of Solution T to the conical flask. 4. Titrate the FA 1 in the conical flask with FA 2 until the solution in the conical flask changes from colourless to a permanent pale blue colour. 5. Record your titration results, to an appropriate level of precision, in the space provided on page 3. 6. Perform sufficient titrations until consistent results are obtained.

3 © Raffles Institution 2026 9476/04/A/26 [Turn Over Results [5] (ii) From your titration results, obtain a suitable volume of FA 2 to be used in your calculations. Show clearly how you obtained this volume. volume of FA 2 = ............................................... [1] (b) (i) Calculate the amount of sodium hydroxide present in the volume of FA 2 in (a)(ii). amount of NaOH = ............................................... [1] (ii) Hence, calculate the total concentration of ethanoic acid and hydrochloric acid in FA 1. total concentration of CH3COOH and HCl = ............................................... [1]

4 © Raffles Institution 2026 9476/04/A/26 [Turn Over (iii) Calculate the concentration of ethanoic acid in FA 1. concentration of CH3COOH = ............................................... [1] (iv) Write the equilibrium constant expression, K1, for reaction 1. [1] (v) Using your answers in (b)(iii) and (b)(iv), calculate the value of K1. K1 = ............................................... [2]

5 © Raffles Institution 2026 9476/04/A/26 [Turn Over (c) Another student proposed to find K1 by carrying out reaction 2 instead. The equilibrium constant for reaction 2 is K2. The student claimed that K1 = 1 K2 and hence, K1 can be calculated. Do you agree with the student? Explain your answer. ………………………………………………………………………………………..………………. ……………………………………………………………………………………………..…………. …………………………………………………………………………………………..………….… …………………………………………………………………………………………………..….[1] (d) The errors associated with each reading using a pipette and burette are ±0.06 cm 3 and ±0.05 cm3 respectively. Calculate the maximum total percentage error of the concentration of ethanoic acid in FA 1. You should assume an average titre result of 20.00 cm3. maximum total percentage error = .............................................[1]

6 © Raffles Institution 2026 9476/04/A/26 [Turn Over (e) FA 3 is an aqueous solution of an alcohol J with molecular formula C5H8O2. You will perform tests to identify the functional groups in J and hence deduce the possible structure for J. 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. Preparation of hot water bath Fill a 250 cm3 glass beaker with 150 cm3 of water, place it on the tripod stand and turn on the Bunsen burner. Once the water is boiling, turn off the Bunsen burner. Use this beaker of hot water for tests 1 and 2 in Table 1.1. (i) Carry out the tests described in Table 1.1. Carefully record your observations in Table 1.1. Table 1.1 tests observations 1 Add 1 cm depth of FA 3 into a clean test-tube. To this test-tube add 10 drops of sodium hydroxide followed by iodine solution, dropwise, until a permanent yellow / orange colour is present. Warm the test-tube in the beaker of hot water for 2 minutes. 2 Add 1 cm depth of FA 3 into a clean test-tube. Add 8 drops of Fehling’s solution. Warm the test-tube in the beaker of hot water for 3 minutes. 3 Test solution FA 3 with Universal Indicator paper. [3]

7 © Raffles Institution 2026 9476/04/A/26 [Turn Over (ii) Alcohol J with molecular formula C5H8O2 has the following features. • It contains one chiral carbon atom. • It decolourises aqueous bromine. • It does not exhibit cis–trans isomerism. Using the above information, together with your observations in Table 1.1, draw the structural formula of J. [1] [Total: 18]

8 © Raffles Institution 2026 9476/04/A/26 [Turn Over 2 Identification of one cation and one anion FA 4 is a solution containing two cations and one anion. One of the cations, M2+, is not found in the Qualitative Analysis Notes. An aqueous solution of M2+ is pink. You will carry out tests to identify the other cation and the anion in FA 4. You need not identify M2+. Test and identify any gases evolved in the tests. If there is no observable change, write no observable change. (a) Carry out the tests in Table 2.1 on FA 4. Carefully record your observations in Table 2.1. Table 2.1 tests observations 1 Add 1 cm d