NYJC H2 Chem Prelim P2 QP

[Turn Over NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS TUTOR’S NAME CHEMISTRY 9729/02 Paper 2 Structured Questions 11 SEP 2017 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams, 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. 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 /13 2 /23 3 /14 4 /11 5 /14 Total /75 This document consists of 22 printed pages. KiasuExamPaper.com

2 NYJC 2017 H2 Chemistry 9729/02 PRELIM For Examiner's Use 1 A mmonium salts are commonly used in instant cold packs. The cold pack contains water and an inner pouch containing an ammonium salt. When the pack is squeezed, this inner pouch breaks and releases the salt, which quickly dissolves and lowers the pack’s temperature. To determine whether ammonium chloride or ammonium nitrate is more effective as the ingredient in the cold pack, a student decided to conduct an experiment to find out the enthalpy change of solution of the two salts, starting with ammonium chloride. He added ammonium chloride to water and found the temperature change by plotting a suitable graph to correct for heat transfer. In a preliminary investigation, the enthalpy change of solution of ammonium chloride was found to be approximately +15 kJ mol –1 . (a) (i) Draw dot-and-cross diagram to illustrate the bonding in ammonium nitrate. Hence state the shape with respect to each nitrogen atom. [3] (ii) The student predicted that enthalpy change of solution of ammonium nitrate is more endothermic compared to ammonium chloride. Explain why his prediction is correct. ……………………………………………………………………………………...…. …………………………………………………………………………………….…... ……………………………………………………………………………………...…. …………………………………………………………………………………….…... ………………………………………………………………………….……………… ………………………………………………………………………………………[2] KiasuExamPaper.com

3 NYJC 2017 H2 Chemistry 9729/02 PRELIM [Turn Over For Examiner's Use (b) (i) The student was to