RVHS_H2_CHEM_P2_Ans 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

2 River Valley High School 9647/02/PRELIM II/16 2016 Preliminary Examination II 1 (a) (i) [1] (ii) Amount of salicylic acid in 10 g = 138 10 = 0.0725 mol Theoretical amount of salicylic acid = 60 0725.0 × 100 = 0.121 mol Amount of methyl salicylate required = 0.121 mol Mass of methyl salicylate required = 0.121 × 152 = 18.4 g Volume of methyl salicylate required = 174.1 4.18 = 15.7 cm3 Amount of sodium hydroxide required = 0.121 × 2 = 0.242 mol Volume of sodium hydroxide required = 0.6 242.0 ×1000 = 40.3 cm3 [2] (b) Water out Liebig condenser Liebig condenser Liebig condenser (Liebig) condenser Water in (100 cm3) round bottom flask containing reaction mixture Heating mantle

3 River Valley High School 9647/02/PRELIM II/16 [Turn over 2016 Preliminary Examination II 1. Using a 25 cm3 measuring cylinder, measure 16 cm3 (accept up to 20 cm 3) of methyl salicylate and place it in a 100 cm3 round bottom flask. 2. Using a 50 cm3 measuring cylinder, measure 41 cm3 (accept up to 50 cm3) of aqueous sodium hydroxide and place it into the 100 cm 3 round bottom flask. Add some boiling chips to the mixture. 3. Set up the reflux set -up shown in the above diagram and heat the mixture for 30 minutes. 4. Allow the reaction mixture to cool down to room temperature and remove the boiling chips. 5. Place the round bottom flask in an ice bath. 6. Add concentrated hydrochloric acid to the reaction mixture slowly, with stirring. 7. Test the acidity of the mixture with a blue litmus paper. 8. Filter the mixture and wash the residue (crude salicylic acid) with a small amount of cold water. 9. Transfer the crude salicylic acid to a clean 100 cm 3 conical flask. Add a small volume of water and heat the mixture until all the cru