2025 JC2 Prelims H2 Chem Paper 4 QP_TJC

9729 / TJC Prelim / 2025 [Turn Over TEMASEK JUNIOR COLLEGE 2025 JC2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS CENTRE NUMBER S INDEX NUMBER Chemistry 9729/04 Paper 4 Practical 28 August 2025 2 hours 30 minutes Candidates answer on the Question Paper. READ THESE INSTRUCTIONS FIRST Write your name, CG, centre number 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 an 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. 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. This document consists of 19 printed pages and 1 blank page. For Examiner’s Use 1 2 3 4 Total Shift Laboratory

2 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelim / 2025 Answer all the questions in the spaces provided. 1 Determination of the percentage by mass of iron in the wire Iron wire contains impurities. In this experiment, you will investigate the percentage by mass of iron in a sample of iron wire. A sample of iron wire is reacted with an excess of sulfuric acid to produce a solution of iron( II) sulfate. You will titrate the solution of iron( II) sulfate with potassium manganate( VII) of known concentration to determine the amount of iron( II) ions present and hence percentage by mass of iron in the wire. You may assume that impurities do not react with potassium manganate(VII). Iron(II) ions react with manganate(VII) ions according to the equation shown. 5Fe2+ + MnO4– + 8H+ → 5Fe3+ + Mn2+ + 4H2O FA 1 is 0.0200 mol dm–3 potassium manganate(VII), KMnO4. FA 2 is a diluted solution of FeSO4 prepared as follows: • 48.9 g of iron wire was reacted with sulfuric acid to make 1.00 dm3 of solution. • 34.00 cm3 of the solution was then made up to 250 cm3 with deionised water. FA 3 is dilute sulfuric acid, H2SO4. (a) (i) Procedure 1. Fill the burette with FA 1. 2. Pipette 25.0 cm3 of FA 2 into a 250 cm3 conical flask. 3. Use a measuring cylinder to add 25 cm3 of FA 3 into the conical flask. 4. Add FA 1 from the burette until the solution in the conical flask turns to a permanent pale pink colour. 5. Record your titration results, to an appropriate level of precision in the space on page 3. 6. Repeat steps 2 to 5 until consistent results ar