2024 ASRJC H2 Chemistry Prelim P4 (QP)

ASRJC JC2 PRELIM 20248 9729/04/H2 [Turn Over ANDERSON SERANGOON JUNIOR COLLEGE 2024 JC 2 PRELIMINARY EXAMINATION NAME:________________________________ ( ) CLASS: 24 /____ CHEMISTRY 9729/04 Paper 4 Practical 21 August 2024 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 23 and 24. 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 / 16 2 / 14 3 / 16 4 / 9 Total / 55 This document consists of 20 printed pages.

2 ASRJC JC2 PRELIM 20248 9729/04/H2 Answer all the questions in the spaces provided. 1 Investigation of the kinetics of the catalysed decomposition of hydrogen peroxide Hydrogen peroxide decomposes very slowly to form water and oxygen gas as shown in equation 1. equation 1 2H2O2 2H2O + O2 Many transition element ions are able to catalyse the decomposition of hydrogen peroxide. Iron(III) nitrate, Fe(NO3)3, is an effective catalyst for this reaction. FA 1 is 0.170 mol dm-3 aqueous hydrogen peroxide, H2O2 FA 2 is 0.2 mol dm-3 sulfuric acid, H2SO4 FA 3 is 0.020 mol dm-3 potassium manganate(VII), KMnO4 You are also provided with iron(III) nitrate, Fe(NO3)3 You will add a measured volume of iron(III) nitrate to a measured volume of FA 1 and, at timed intervals, transfer aliquots (portions) of the reaction mixture to titrate remaining H 2O2 against KMnO4 in FA 3. Acidified KMnO4 and H2O2 react as shown in equation 2. equation 2 2MnO4–(aq) + 5H2O2(aq) + 6H+(aq) 2Mn2+(aq) + 8H2O(l) + 5O2(g) (a) (i) Preparation and titration of the reaction mixture Notes: You will perform each titration once only. Great care must be taken that you do not overshoot the end-point. Once you have started the stopwatch, it must continue running for the duration of the experiment. You must not stop it until you have finished this experiment. You should aim to transfer your first aliquot within the first three minutes of starting the reaction. You should aim not to exceed a maximum reaction time of 25 minutes for this experiment.

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