TMJC 2022 H2 Chem Prelim P4 (QP)

CANDIDATE NAME CIVICS GROUP 21S H2 CHEMISTRY 9729 / 04 Paper 4 Practical 30 August 2022 2 hours 30 minutes Candidates answer on the Question Paper. This document consists of 22 printed pages. READ THESE INSTRUCTIONS FIRST Write your name and Civics Group in the spaces at the top of the page. 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 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 21 and 22. The number of marks is given in brackets [ ] at the end of each question or part question. Shift 1 / 2 / 3 Laboratory For Examiner’s Use 1 / 11 2 / 20 3 / 10 4 / 14 Total / 55 TAMPINES MERIDIAN JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION

2 Tampines Meridian Junior College 2022 JC2 Preliminary Exam H2 Chemistry 1 Determination of water of crystallisation in a hydrated iron(III) salt A variety of hydrated iron(III) sulfates are known. Solutions of iron(III) sulfate are used in dyeing, and as coagulant for industrial waste. FA 1 is a solution containing 26.0 g dm–3 of hydrated iron(III) sulfate, Fe2(SO4)3.nH2O. The addition of excess zinc to a solution of FA 1 reduces the Fe3+ ions to Fe2+ ions. The amount of Fe2+ ions can be determined quantitatively by 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 are to perform titrations to determine the value of n, the water of crystallisation in FA 1. You are provided with FA 1, solution containing 26.0 g dm–3 of hydrated iron(III) sulfate, Fe2(SO4)3.nH2O. FA 2, dilute sulfuric acid, FA 3, 0.0200 mol dm−3 potassium manganate(VII), KMnO4, zinc powder . (a) Preparation of Fe2+ solution from FA 1 1. Use a measuring cylinder to transfer 80 cm3 of FA 1 into a 250 cm3 beaker. 2. Add all the zinc powder into the beaker. Cover the beaker with a white tile. 3. Allow the reaction to take place for about 5 minutes, stirring the reaction mixture from time to time. 4. Filter the mixture into the dry beaker provided using a dry filter paper and filter funnel. Ignore any reaction that may still be taking place. 5. Label the filtrate as FA 4. Proceed to 1(b) once you have collected sufficient filtrate. (b) Titration of FA 4 against FA 3 6. Fill the burette labelled FA 3 with FA 3. 7. Use a pipette to transfer 10.0 cm3 of FA 4 into a 100 cm3 conical flask. 8. Use a measuring cylinder to add 10 cm3 o