NYJC 2020 Prelim 9729 P4

[Turn over NANYANG JUNIOR COLLEGE JC2 PRACTICAL PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS 1 9 TUTOR CENTRE NUMBER S INDEX NUMBER CHEMISTRY 9729/04 Paper 4 Practical 19 August 2020 2 hour 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 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 an HB pencil for any diagrams or graphs Do not use staples, paper clips, highlighters, 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. Shift 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 17 and 18. Laboratory 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. For Examiner’s Use 1(c), (d), (f) [5] 3(a) [8] 1 / 10 1(e) [5] 3(b) [2] 2 / 18 2(a) [7] 4(a)-(c) [6] 3 /10 2(b), (c) [6] 4(d)-(g) [6] 4 / 17 2(d), (e) [5] 4(h)-(k) [5] Total /55 This document consists of 18 printed pages and 2 blank pages.

2 H2 Chemistry 9729/04 NYJC J2/20 PX Answer all the questions in the spaces provided. 1 Investigation of the extraction of propanoic acid from the aqueous layer by an organic liquid Propanoic acid has different solubilities in water and in the organic liquid, FB 6. When an aqueous solution of propanoic acid is shaken with FB 6, two separate layers, an aqueous layer and an organic layer will be observed. Some of the acid dissolves in the organic layer. The amount of acid remaining in the aqueous layer can be determined by titration with aqueous sodium hydroxide. FA 1 is 0.050 mol dm–3 sodium hydroxide solution. FA 2 is 0.200 mol dm–3 propanoic acid, C2H5COOH. FB 6 is an organic liquid that does not mix with water. (a) Preparation of the mixture in Flask A. 1. Flask A is a stoppered flask that contains 40 cm3 of FB 6. 2. Use a 50 cm3 measuring cylinder to place 50 cm3 of FA 2 into Flask A. 3. Replace the stopper in the flask. 4. Shake the flask vigorously for about 1 minute. 5. Leave the flask to stand on the workbench for about 10 minutes. 6. Shake the flask vigorously again for about 1 minute during the 10 minute duration. While the flask is standing on the workbench, you may move on to the next question. (b) Titrations 1. Fill the burette with FA 1. 2. Ensure the two layers in Flask A have separated – this should take no longer than 1 minute after shaking the flask. 3. Pipette 10.0 cm 3 of the lower (aqueous) layer into a conical