2024 JPJC Chem Prelim Paper 4 Ans slides

© Jurong Pioneer Junior College [Turn Over NAME Answer slides CLASS 23S JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2024 CHEMISTRY 9729/04 Higher 2 Paper 4 Practical 13 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 exam 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, 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 20 and 21. Shift At the end of the examination, fasten all your work securely together. Laboratory The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 14 2 / 18 3 / 11 4 / 12 Total / 55 This document consists of 21 printed pages.

2 © Jurong Pioneer Junior College 9729/04/J2 PRELIMINARY EXAM/2024 Answer all the questions in the spaces provided. 1 Investigation of some inorganic and organic reactions You are provided with the following samples: FA 1 is an aqueous solution of an organic compound, Y. FA 2 is an aqueous solution of an organic compound, Z, which is an isomer of Y. FA 3 is a solid sample with molecular formula XOn, where X is a metal. You will perform tests to identify: • the structure of Y in FA 1 • the functional group of Z in FA 2 • the cation in FA 3 (a) (i) Perform the tests described in Table 1.1, and record your observations in the table. Table 1.1 tests observations 1 To 1 cm depth of FA 1 in a test-tube, add a small piece of sodium. No observable change. 2 To 1 cm depth of aqueous AgNO 3 in a test-tube, add 1 cm depth of aqueous NaOH. Then add aqueous NH3 until the precipitate just dissolves. To this mixture, add 1 cm depth of FA 1. Heat the mixture in the hot water- bath. Brown ppt. (✓1) dissolves to give a colourless solution. (✓2) Upon warming with FA 1, no silver mirror (or no grey ppt.) (or no observable change). (✓3*) 3 To 1 cm depth of FA 1 in a test-tube, add 10 drops of aqueous sodium hydroxide. Now add aqueous iodine dropwise, until a permanent yellow/orange colour is obtained. Warm the mixture in the hot water bath for 2 minutes. pale yellow ppt. (✓4*) formed. [2] Redox rxn. H2? Identify —OH in alcohol, phenol & RCOOH. No —OH group  alcohol, phenol & RCOOH absent. Preparing Tollens’ reagent, Ag(NH3)