2022 YIJC H2 CHEM PRELIM P3 QP

©YIJC [Turn over YISHUN INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CG INDEX NO CHEMISTRY Paper 3 Free Response Candidates answer on the Question Paper. Additional Materials: Data Booklet 9729/03 12 September 2022 2 hours READ THESE INSTRUCTIONS FIRST This document consists of 31 printed pages and 1 blank page For Examiner’s Use Section A 1 / 17 2 / 18 3 / 25 Section B 4 or 5 / 20 Penalty units significant figures Overall / 80 Write your name, class and index number on all the work you hand in. Write in dark blue or black pen on both sides of the paper. 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 question number must be clearly shown. Section A Answer all the questions. Section B Answer one question. 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.

2 ©YIJC [Turn over Section A Answer all the questions in this section. 1 (a) Describe and explain the trend in the thermal stability of the hydrogen halides, HCl, HBr and HI. Include an equation for the thermal decomposition reaction in your answer. [3] (b) Alkanes are generally considered to be unreactive compounds, showing an inertness to common reagents such as NaOH, H2SO4, and K2Cr2O7. (i) Suggest a reason why these reagents do not react with an alkane such as propane. [1] Propane can be converted into 2-chloropropane when it reacts with chlorine in ultraviolet (UV) light. (ii) Describe the mechanism of the reaction between propane and chlorine in UV light. [3]

3 ©YIJC [Turn over (c) (i) Define the term lattice energy. [1] (ii) Use the data in Table 1.1, together with data from the Data Booklet, to calculate a value for the lattice energy of silver iodide, AgI(s). Show your working. Table 1.1 value / kJ mol−1 electron affinity of iodine, I(g) + e− → I−(g) −295 enthalpy change of sublimation of iodine molecules, I2(s) → I2(g) +62 standard enthalpy change of atomisation