2022 TJC Prelims H2 Paper 4 Qns and Ans

1 [Turn over DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelim / 2022 CANDIDATE NAME CIVICS GROUP / CENTRE NO. / INDEX NO. / CHEMISTRY 9729/04 Paper 4 Practical 29 August 2022 2 hours 30 minutes Candidates answer on the Question Paper. READ THESE INSTRUCTIONS FIRST Write your Civics Group and name 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 23 and 24. 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 22 printed pages and 2 blank pages. For Examiner’s Use 1 / 12 2 / 19 3 / 14 4 / 10 Total / 55 Shift Laboratory 2022 JC2 PRELIMINARY EXAMINATIONS HIGHER 2

2 [Turn over DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelim / 2022 Answer all the questions in the spaces provided. 1 Determination of the percentage by mass of water of crystallisation in FeSO4·nH2O Read through the whole method before starting any practical work. Where appropriate, prepare a table for your results in the space provided. Show your working and appropriate significant figures in the final answer to each step of your calculations. The amount of Fe2+ ions can be determined quantitatively by a titration against a standard solution of potassium manganate(VII), KMnO4. The reaction is shown below. 5Fe2+ + MnO4− + 8H+ → 5Fe3+ + Mn2+ + 4H2O In this experiment, you will determine the percentage by mass of water of crystallisation in FeSO4·nH2O. You will titrate a solution of FA 1 against FA 3. You are provided with FA 1, contains 26.07 g dm–3 of hydrated iron(II) sulfate, FeSO4•nH2O, where n is an integer. FA 2, 1.0 mol dm-3 dilute sulfuric acid, H2SO4. FA 3, 0.0200 mol dm−3 potassium manganate(VII), KMnO4, You are to keep FA 2 and FA 3 for questions 2 and 3. (a) (i) Titration of FA 1 against FA 3 1. Fill a burette, labelled FA 3, with FA 3. 2. Use a pipette to transfer 10.0 cm3 of FA 1 into a 250 cm3 conical flask. 3. Use a measuring cylinder to add about 10 cm3 of FA 2 to this flask. 4. Titrate FA 1 with FA 3 from the burett