2019 HCI Prelim H2 Chem P2 QP

This document consists of 16 printed pages. HWA CHONG INSTITUTION C2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 18S CENTRE NUMBER INDEX NUMBER CHEMISTRY Paper 2 Structured Questions Candidates answer on the Question Paper Additional Materials: Data Booklet 9729/02 18 September 2019 2 hours READ THESE INSTRUCTIONS FIRST Write your name, CT group, centre number and index number clearly in the spaces above. Write in dark blue or black pen. You may use a HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided in the Question Paper. The use of an approved scientific calculator is expected, where appropriate. 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 / 17 2 / 13 3 / 22 4 / 23 s.f. units Total / 75 Calculator Model:

2 © Hwa Chong Institution 2019 9729 / 02 / C2 Prelim 2019 1 (a) Butanone can be converted to compound C via the following series of reactions. (i) Suggest the reagents and conditions for step 1. ……………………………………………………………………………………………... [1] (ii) In the boxes below, draw the structures of compounds A, B and C. A B C [3]

3 © Hwa Chong Institution 2019 9729 / 02 / C2 Prelim 2019 (b) 2-iodobutane is converted to its corresponding alcohol by heating with aqueous sodium hydroxide. ∆H < 0 The rate equation is: rate = k[2-iodobutane][NaOH] (i) Describe the mechanism of this reaction. In your answer you should show all charges and lone pairs and show the movement of electrons by curly arrows. [3] (ii) Draw a fully labelled reaction pathway diagram for the reaction between 2-iodobutane and sodium hydroxide. [2] (c) Describe and explain how the volatilities of the halogens vary from chlorine to iodine. ....………………………..………………………………………………………………………...... ....………………………..………………………………………………………………………...... ..………………………..…………………………………………………………..……………...... ..………………………..…………………………………………………………..……………...... ..………………………..……………………………………………………….……………….. [2]

4 © Hwa Chong Institution 2019 9729 / 02 / C2 Prelim 2019 (d) Some hydrogen halides are unstable to heat. (i) Write an equation for the reaction undergone on heating a hydrogen halide. ……………………………………………………………………………………………... [1] (ii) Describe and explain how the thermal stabilities of the hydrogen halides (HC l, HBr and HI) vary down the group. ....………………………..……