2020 JPJCPrelim Paper 4 suggested solutions

 Jurong Pioneer Junior College [Turn Over NAME CLASS 19S JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2020 CHEMISTRY 9729/04 Higher 2 Paper 4 Practical 2 September 2020 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. Do not spend more than 40 minutes on Q1 and Q2. 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 18 and 19. 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 /8 2 /9 3 /22 4 /16 Total /55 This document consists of 19 printed pages.

2  Jurong Pioneer Junior College 9729/04/J2 PRELIMINARY EXAM/2020 Answer all the questions in the spaces provided. 1 Inorganic Qualitative Analysis FA 1 is a solid sample which contains two cations and one anion. One of the cations is Fe3+. Perform the tests described in Table 1.1 and record your observations in the table. Test and identify any gases evolved. If there is no observable change, write no observable change. For Examiner’s Use Table 1.1 tests observations (a) (i) Add one spatula full of FA 1 into a test-tube. Place about 5 cm depth of deionised water into the test -tube and shake the mixture until all the solid has dissolved. Use this FA 1 solution for tests (ii) and (iii). Lilac solid dissolves to give yellow / orange / brown solution. () (ii) To a 2 cm depth of FA 1 solution in a test -tube, add a small spatula of solid sodium carbonate. Red-brown/brown/orange-brown ppt. () Effervescence () observed. CO2 () gas gives a white ppt. with limewater. () (iii) To a 1 cm depth of FA 1 solution in a boiling tube , add aqueous sodium hydroxide dropwise, with shaking, until it is in excess. Gently warm the mixture. Then filter the mixture, collecting the filtrate in a clean test-tube. Keep the filtrate for test (iv). Red-brown/brown/orange-brown ppt. () insoluble in excess NaOH. () Pungent NH3 () gas turns damp red litmus paper blue. () Red-brown/brown/orange-brown residue () and colourless filtrate () (iv) To a 1 cm depth of the filtrate from test (iii)