2023 ACJC H2 Chem Prelim Paper 3 Suggested Solutions

1 © ACJC2023 9729/03/Prelim/2023 Anglo-Chinese Junior College JC2 Preliminary Examination Higher 2 CANDIDATE NAME SUGGESTED SOLUTIONS FORM CLASS TUTORIAL CLASS INDEX NUMBER CHEMISTRY Paper 3 Free Response Candidates answer on the Question Paper. Additional Materials: Data Booklet 9729/03 28 August 2023 2 hours READ THESE INSTRUCTIONS FIRST Write your index number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. If additional space is required, you should use the pages at the end of this booklet. The que stion number must be clearly shown. Section A Answer all questions. Section B Answer one question. Circle the number of the question you have attempted. A Data Booklet is provided. The use of an approved scientific calculator is expected, where appropriate. 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 Examiners’ use only Section A 1 / 17 2 / 18 3 / 25 Section B 4 / 5 / 20 Total / 80 This document consists of 24 printed pages.

2 © ACJC2023 9729/03/Prelim/2023 Section A Answer all the questions in this section. 1 Ibuprofen belongs to a class of drugs called non-steroidal anti-inflammatory drugs (NSAIDs) used to reduce inflammation, pain and fever. Pain, fever, and inflammation are caused by the release in the body of chemicals called prostaglandins. Ibuprofen block s the enzyme that makes prostaglandins resulting in lower levels of prostaglandins. The following diagram shows the first step in the synthesis route to form ibuprofen from compound A. (a) A series of experiments were carried out at 25 °C to find the effect of initial concentration of hydrogen cyanide, cyanide ions and A on the initial rate of formation of B. Table 1.1 experiment initial concentration / mol dm−3 initial rate of formation of B / mol dm−3 s−1 [A] [HCN] [CN−] 1 0.020 0.060 0.060 1.00 2 0.020 0.050 0.050 0.833 3 0.020 0.050 0.060 1.00 4 0.025 0.050 0.050 1.042

3 © ACJC2023 9729/03/Prelim/2023 (i) Write a balanced equation for the reaction that produces compound B. [1] (ii) Use the data in Table 1.1 to deduce the order of reaction with respect to each of the reactants.