2019 JPJC Prelim H2 Chem P4 QP

 Jurong Pioneer Junior College [Turn Over NAME CLASS 18S JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2019 CHEMISTRY 9729/04 Higher 2 Paper 4 Practical 26 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 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 23 and 24. 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 2 3 4 Total This document consists of 23 printed pages and 1 blank page.

2  Jurong Pioneer Junior College 9729/04/J2 PRELIMINARY EXAM/2019 Answer all the questions in the spaces provided. 1 Determination of the identity of the halogen, X, in CH2XCO2H For Examiner’s Use Compound W is a halogenoethanoic acid, CH2XCO2H, where X is a halogen. A halogenoethanoic acid reacts with aqueous sodium hydroxide in two reactions. The alkali neutralises the carboxylic acid. reaction 1 NaOH + CH2XCO2H  CH2XCO2Na + H2O The halogenoalkyl group then undergoes a substitution reaction. reaction 2 NaOH + CH2XCO2Na  CH2(OH)CO2Na + NaX 4 g of W were heated for one minute with 250 cm3 of 0.4 0 mol dm 3 aqueous sodium hydroxide in a beaker. Some of the sodium hydroxide reacted with compound W as shown by equations 1 and 2. The solution that remained contains unreacted sodium hydroxide. This solution is FA 1. In 1(a), you will perform a dilution and by titrating FA 1 with the diluted sulfuric acid, y ou will determine the identity of X in CH2XCO2H. FA 1 is aqueous sodium hydroxide after reaction with W. FA 2 is 2.00 mol dm3 sulfuric acid, H2SO4. methyl orange indicator (a) (i) Dilution of FA 2 1. Use a pipette to transfer 10.0 cm3 of FA 2 into a 250 cm3 volumetric flask. 2. Make up the contents of the flask to the 250 cm 3 mark with deionised water. 3. Place the stopper in the flask and mix the contents thoroughly by slowly inverting the flask a number of times. 4. Label this diluted solution of sulfuric acid as FA 3. (ii) Titration of FA 1 against FA 3 1. Fill the burette labelled FA 3, with FA 3. 2.