2019 ASRJC Prelim H2 Chem P4 QP

ASRJC JC2 PRELIMS 2019 9729/04/H2 [Turn over ANDERSON SERANGOON JUNIOR COLLEGE 2019 JC 2 PRELIMINARY EXAMINATIONS NAME:______________________________ ( ) CLASS: 19 /____ CHEMISTRY 9729/04 Paper 4 Practical 27 August 2019 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 pencil for any diagrams, graphs or rough working. 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 22 and 23. 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 For Examiner’s Use 1 Laboratory 2 3 Total This document consists of 23 printed pages.

2 ASRJC JC2 PRELIMS 2019 9729/04/H2 Answer all the questions in the spaces provided. 1 To determine the order of reaction with respect to the concentration of iodine in the iodination of propanone reaction FA 1 is 1.00 mol dm–3 propanone, CH3COCH3 FA 2 is 1.00 mol dm–3 sulfuric acid, H2SO4 FA 3 is an aqueous solution of iodine, I2 FA 4 is 0.0100 mol dm–3 sodium thiosulfate, Na2S2O3 FA 5 is 0.50 mol dm–3 sodium hydrogencarbonate, NaHCO3 You are also provided with a starch indicator. The iodination of propanone, to form iodopropanone, proceeds as shown in the equation below. Reaction 1: CH3COCH3(aq) + I2(aq) → CH3COCH2I(aq) + HI(aq) This reaction is first order with respect to both CH3COCH3 and H+ ions. You are to investigate the order of reaction with respect to I2. A reaction mixture containing FA 1, FA 2, and FA 3 is first prepared . At different chosen times, aliquots (fixed volumes) of this reaction mixture is removed and quenched using excess FA 5. The remaining amount of I2 at different times can then be determined by titration against FA 4. Each titration can only be performed once. Reaction 2: 2S2O32–(aq) + I2(aq) → 2I–(aq) + S4O62–(aq) The required order of reaction can be obtained by the graphical analysis of your results. The first aliquot should be removed approximately 4 minutes after the reagents were mixed. You will then remove four further aliquots, at time intervals of your choice, up to