NYJC Prelim H2 Chem 9729 P4

[Turn Over H NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME TUTOR’S NAME CLASS CHEMISTRY 9729/04 Paper 4 Practical 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 and class 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 an 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 19 and 20. 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 / 13 2 / 15 3 / 14 4 / 13 Total / 55 This document consists of 20 printed pages

2 H2 Chemistry 9729/04 NYJC J2/2025 PRELIM 1 Determination of concentration of ethanedioic acid FA 1 is 0.023 mol dm–3 potassium manganate(VII), KMnO4. FA 2 is aqueous ethanedioic acid, H2C2O4, made by dissolving the hydrated salt, H2C2O4∙2H2O. You are also provided with 1.0 mol dm–3 sulfuric acid, H2SO4. In this experiment you are to determine the concentration, in g dm–3, of hydrated ethanedioic acid, H2C2O4∙2H2O, in FA 2. (a) Manganate(VII) ions, MnO4–, and ethanedioate ions, C2O42‒, undergo redox reaction in an acidic solution. Fill in the stoichiometric values for the reaction equation below. MnO4– + H+ + C2O42– → Mn2+ + H2O + CO2 [1] (b) Dilution of FA 2 1. Using a burette, measure between 42.50 cm3 and 43.00 cm3 of FA 2 into a 250 cm3 volumetric flask. Record the data in the space provided below. 2. Make the solution up to the mark with deionised water and shake well to mix. 3. Label this solution FA 3. Results

3 H2 Chemistry 9729/04 NYJC J2/2025 PRELIM [Turn Over Titration of FA 3 against FA 1 4. Fill a second burette with FA 1. 5. Use a pipette to transfer 25.0 cm3 of FA 3 into a 250 cm3 conical flask. 6. Using a measuring cylinder, transfer 25.0 cm3 of 1.0 mol dm–3 sulfuric acid and 40.0 cm3 of deionised water into the same flask and place the flask on a tripod stand. 7. Put a thermometer into the conical flask and heat the solution using a Bunsen flame until the temperature of the solution is just above 65 ºC. 8. Carefully remove the thermometer and place the flask under the second burette containi