2025 ASRJC Prelim H2Chem P4_QP

ASRJC JC2 Prelim 2025 9729/04/H2 ANDERSON SERANGOON JUNIOR COLLEGE 2025 JC2 Preliminary Examination NAME:________________________________ ( ) CLASS: 25 /____ CHEMISTRY 9729/04 Paper 4 Practical 19 August 2025 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 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 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. Quantitative Analysis Notes are printed on pages 19 and 20. Shift Laboratory 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. For Examiner’s Use 1 / 19 2 / 18 3 / 8 4 / 10 Total / 55 This document consists of 19 printed pages and 1 blank page.

2 ASRJC JC2 Prelim 2025 9729/04/H2 1 Determination of an enthalpy change of neutralisation, ∆Hneut, by thermometric titration The enthalpy change of neutralisation between an acid and an alkali can be determined using thermometric titration. This involves using a fixed volume of alkali with progressive addition of small volumes of acid and monitoring the temperature of the reaction mixture during the process. FA 1 is an aqueous solution of 1.80 mol dm-3 of a monobasic acid, HA. FA 2 is aqueous sodium hydroxide, NaOH You are to carry out a thermometric titration to determine the enthalpy change of neutralisation for the reaction given below. HA(aq) + NaOH(aq) → NaA(aq) + H2O(l) Question continues on Page 4.

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4 ASRJC JC2 Prelim 2025 9729/04/H2 (a) Prepare a table in the space provided and record, to appropriate level of precision: • all volumes of FA 1 added, V • the maximum temperature, T, reached after each addition of FA 1. It is important that the volume of FA 1 recorded is the total volume you have added up to the point when the temperature reading was made. Note: If you overshoot on an addition, record the actual total volume of FA 1 added up to that point. Procedure 1. Place a polystyrene cup inside a second polystyrene cup and place both cups in a glass beaker. 2. Fill the burette with FA 1. 3. Use a measuring cylinder to transfer 25 cm3 of FA 2 into the polystyrene cup. 4. Stir the FA 2 solution in the cup gently with the thermometer. Read and record its temperature. 5. Use the burette to ad