RI 2022 Prelim P2 QP

© Raffles Institution 2022 9729/02/S/22 [Turn Over RAFFLES INSTITUTION 2022 YEAR 6 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 9729/02 Paper 2 Structured Questions 14 September 2022 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Do not open this question booklet until you are told to do so. Write your name, class and index number in the spaces at the top of this page. 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. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. Do not write anything in it. You are reminded of the need for good English and clear presentation in your answers. 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 / 19 2 / 20 3 / 19 4 / 17 Total / 75 This document consists of 24 printed pages and 4 blank pages.

2 For examiner’s use Answer all questions in the space provided. 1 This question is about the compounds of iodine and their reactions. (a) Hydrogen iodide is a primary source of iodine in chemical reactions. It can be synthesised from iodine via the following two steps. step 1 3I2 + 2P ⎯→ 2PI3 step 2 PI3 + 3H2O ⎯→ 3HI + H3PO3 Given that 65 cm 3 of HI gas is collected at standard temperature and pressure, calculate the mass of iodine reacted. [2] (b) (i) Explain the trend and variation in the boiling points of the hydrogen halides shown in the table below. hydrogen halide HF HCl HBr HI boiling point / oC +20 −85 −67 −35 …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………….…. ……………………………………………………………………………………………… [2]

3 For examiner’s use (ii) Describe and explain the trend in the thermal stability of HCl, HBr and HI. .…………………………………………………………………………………………………. .…………………………………………………………………………………………………. .…………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………… [2] (c) Iodate(V) ion, IO3– , is commonly used as an oxidising agent in chemical reactions. (i) Draw a ‘dot-and-cross’ diagram of IO3–. [1] (ii) With reference to the Valence Shell Electron Pair Repulsion theory , s tate and explain the shape and bond angle about the iodine atom in IO3