2024 CJC H2 Chemistry Prelim P4 (Ans)

[Turn over 9729/04/CJC JC2 Preliminary Examinations 2024 CANDIDATE NAME CLASS 2T 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 and class in the boxes above. 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 19 and 20. 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 19 printed pages and 1 blank page. Instruction Catholic Junior College JC2 Preliminary Examinations Higher 2 Shift Laboratory For Examiner’s Use 1 / 16 2 / 15 3 / 16 4 / 8 Total / 55 MARK SCHEME

2 9729/04/CJC JC2 Preliminary Examinations 2024 Answer all the questions in the spaces provided. 1 Part 1: Qualitative analysis of an inorganic solid mixture FA 1 is a solid mixture that contains two cations and two anions listed in the Qualitative Analysis Notes on pages 19 and 20. Unless otherwise stated, the volumes given below are approximate and should be estimated rather than measured. 1. Add 3 full spatulas of FA 1 into a boiling tube and add 3 cm depth of deionised water. 2. Using a glass rod, stir the mixture for one minute until no more of the solid mixture can dissolve. 3. Filter the mixture into another clean boiling tube. This is the filtrate. While waiting, you may wish to proceed to Question 2 first. 4. When the filtration is completed, p lace the filter funnel containing the residue on a conical flask and wash the residue with a little deionised water. Keep both filtrate and residue for tests (a) and (b) below. Test and identify any gases evolved. At each stage of any test, you are to record details of the following: • colour changes seen • the formation of any precipitate • the solubility of such precipitates in an excess of the reagent added. If there is no observable change, write no observable change. Record your observations in Tables 1.1 and 1.2 below. No additional tests for ions present should be attempted. (a) Tests on the filtrate. Table 1.1 test observations (i) To 1 cm depth of the filtrate in a test - tube, add aqueous sodium hydroxide dropwise, with shaking, until no further change i