NYJC H2 Chem 2012 Prelim P2 QP

NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS 1 1 INDEX NO. TUTOR CHEMISTRY 9647/02 Paper 2 Structured 10 September 2012 2 hours Candidates answer on the Question Paper Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions in the spaces provided. A Data Booklet is provided. 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 P /12 2 / 8 3 / 7 4 / 14 5 / 6 6 / 4 7 / 8 8 / 9 /609 / 4 This document consists of 16 printed pages and 0 blank page. [Turn over

2 H2 Chemistry 9647/02 NYJC J2/12 PX [Turn over For Examiner's Use Answer all questions in the spaces provided. 1 Planning (P) Paracetamol (acetaminophen) is commonly used for the relief of headaches and is a major ingredient in numerous cold and flu medicine. It is a white solid (m.p. = 169 oC) which can be prepared by a reaction between 4-aminophenol and ethanoic anhydride. HOC 6H4NH2 (CH3CO)2O CH 3CONHC6H4OH 4-aminophenol (Mr = 109) ethanoic anhydride (Mr = 102) paracetamol (Mr = 151) A typical yield, based on 4-aminophenol, is 70%. The crude product can be purified by recrystallisation from water. The purity of the recrystallised product can be confirmed by determining its melting point. Ethanoic anhydride can cause irritation of tissue, especially in nasal passages. 4-aminophenol is a skin irritant and is toxic. (a) Using the information above: (i) Write a balanced equation for the formation of paracetamol; (ii) Calculate the minimum masses of reactants needed to prepare 5 g of pure paracetamol. [3]

3 H2 Chemistry 9647/02 NYJC J2/12 PX [Turn over For Examiner's Use (b) Write a full description of the purification of the crude paracetamol. List the essential apparatus you would use in the process. You do not have to describe the preparation of paracetamol. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. ......................................................................................................................