RI H2 Chem 2013 Prelim P2 QP

© Raffles Institution 2013 9647/02/S/13 [Turn over RAFFLES INSTITUTION 2013 YEAR 6 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 9647/02 Paper 2 Structured Questions 18 September 2013 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet. READ THESE INSTRUCTIONS FIRST Write your name, class and index number on all the work you hand in. Write in dark blue or black pen in the spaces provided. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. A Data Booklet is provided. Do not write anything on it. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 12 2 / 13 3 / 11 4 / 10 5 / 18 6 / 8 Total / 72 This document consists of 22 printed pages. 181

2 © Raffles Institution 2013 9647/02/S/13 [Turn over 1 Planning (P) The standard enthalpy change of isomerisation, , measures the enthalpy change when 1 mole of a cis–alkene isomerises to 1 mole of the corresponding trans–alkene under standard conditions: However, this enthalpy change cannot be measured directly by experiment. A student decided to determine the standard enthalpy change of isomerisation of cis–hex–3–ene to trans–hex–3–ene using their respective standard enthalpy changes of combustion, . Both alkenes are volatile liquids at 298 K. From his literature review, the student found the of cis–hex–3–ene to be –3733 kJ mol–1. However, the of trans–hex–3–ene was not available. For Examiner’s Use (a) Write a balanced equation, with state symbols, to describe the standard enthalpy change of combustion, , of cis–hex–3–ene, C6H12. ………………………………………………………………………………………... [1] (b) To determine the standard enthalpy change of combustion of trans–hex–3–ene, the student decided to conduct a flame calorimetric experiment. There are two stages to this experiment: Stage I Calibration of calorimeter set-up (i.e. container and water). In the experiment, the calorimeter set-up must first be calibrated by determining its heat capacity , C, which is the amount of heat required to raise its temperature by 1 K. Stage II Determination of the standard enthalpy change of combustion of trans–hex–3–ene using the calibrated calorimeter set-up. cis–hex–3–ene trans–hex–3–ene (l) (l) 182

3 © Raffles Institution 2013 9647/02/S/13 [Turn over The student carried out the flame