RVHS_H2_CHEM_P2_QP Prelim

River Valley High School 9647/02/PRELIM II/16 [Turn over 2016 Preliminary Examination II RIVER VALLEY HIGH SCHOOL YEAR 6 PRELIMINARY EXAMINATION II CANDIDATE NAME CLASS 6 CENTRE NUMBER S INDEX NUMBER H2 CHEMISTRY 9647/02 Paper 2 Structured Questions 13 September 2016 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class, centre number and index number on all the work you hand in. Write in dark blue or black pen on both sides of 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 space provided. A Data Booklet is provided. Do NOT write anything on it. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Paper 2 Question Number 1 2 3 4 5 6 Total (Paper 2) Marks 12 13 8 9 16 14 72 Paper 1 40 Paper 3 80 Total 192 This document consists of 18 printed pages and 2 blank pages.

2 River Valley High School 9647/02/PRELIM II/16 2016 Preliminary Examination II 1 Planning (P) Salicylic acid is known for its ability to ease aches and pains as well as reduce fevers. Its analgesic and anti-inflammatory properties makes it one of the most important medications needed in a basic health system, placing it on the World Health Organisation Model List of Essential Medicines. It can be synthesised via the alkaline hydrolysis of methyl salicyla te, followed by acidification. methyl salicylate salicylic acid (Mr = 152) (Mr = 138) Methyl salicylate is a liquid with a density of 1.174 g cm3. Aqueous sodium hydroxide used for the hydrolysis has a concentration of 6.0 mol dm3. Like most organic reactions, the yiel d of this reaction is less than 100%. Using the procedure described below, a typical yield of pure salicylic acid is 60%. Methyl salicylate is mixed with aqueous sodium hydroxide in a molar ratio of 1:2. The reaction is heated under reflux conditions for around 30 minutes to form a di-sodium salicylate salt. When the reaction mixture has cooled down, concentrated hydrochloric acid is added until in excess to cause the crude salicylic acid to precipitate. This process is highly exothermic. The crude salicylic acid is then purified by recrystallisation from water. (a) Using the information given above: (i) write a balanced equation for the formation of the di -sodium salicylate salt; [1]

3 River Valley High School 9647/02/PRELIM II/16 [Turn over 2016 Preliminary Examination II (ii) calculate the volumes of methyl salicylate and aqueous sodium hydroxide you would u