2021 EJC Prelims Paper 2_QP

© EJC [Turn Over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examination 2021 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CIVICS GROUP 2 0 – REGISTRATION NUMBER CHEMISTRY Paper 2 Structured Questions 9729/02 16 September 2021 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Do not use paper clips, highlighters, glue or correction fluid. Write your name, civics group, registration number 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. Answer all questions on the Question Paper The number of marks is given in brackets [ ] at the end of each question or part question. A Data Booklet is provided. The use of an approved scientific calculator is expected, where appropriate. For Examiner’s Use Paper 2 1 / 15 2 / 12 3 / 13 4 / 15 5 / 20 Total / 75 This document consists of 19 printed pages and 1 blank page.

2 © EJC 9729/02/J2PE/21 For Examiner’s Use 1 Nitrosyl chloride, NOCl decomposes at temperatures above 100 oC to form nitrogen monoxide and chlorine as shown in the equation below. 2NOCl(g) → 2NO(g) + Cl2(g) (a) A sample of NOCl was allowed to decompose at 127 ºC and 147 atm. Assuming that NOCl behaves ideally, show that its initial concentration is 4.48 mol dm−3. [2] (b) A student pointed out that the assumption in (a) that NOCl behaves ideally is not valid. Suggest and explain two possible reasons why this may be so. ................................ ................................ ................................ ................................ .. ................................ ................................ ................................ ................................ .. ................................ ................................ ................................ ................................ .. ................................ ................................ ................................ ................................ .. ................................ ................................ ................................ .............................. [2]

3 © EJC 9729/02/J2PE/21 [Turn Over For Examiner’s Use (c) The change in the concentration of NOC l was monitored as the decomposition reaction occurred over time. The data obtained is shown in Fig. 1.1. Fig. 1.1 (i) Using Fig. 1.1, show that the reaction is second order with respect to NOCl. [3] (ii) Given that the rate equation is   2 rate NOCk= l , calculate the rate constant of the reaction, stating its units clearly. [2]

4 © EJC 9729/02/J2PE/21 For Examiner’s Use (iii) A second experiment was conducted under the same conditions, but using half the initial concentration of NOCl. On the axes provided b