RI 2021_H2_Chemistry_Prelim_Paper_2

© Raffles Institution 2021 9729/02/S/21 [Turn Over RAFFLES INSTITUTION 2021 YEAR 6 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 9729/02 Paper 2 Structured Questions 14 September 2021 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 provided 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 / 25 2 / 10 3 / 12 4 / 28 Total / 75 This document consists of 23 printed pages and 1 blank page.

2 © Raffles Institution 2021 9729/02/S/21 Answer all the questions in the spaces provided. 1 Esters are sweet smelling compounds with widespread industrial applications. (a) Simple esters are flammable liquids. The standard enthalpy change of combustion for some simple esters can be experimentally determined using the set-up shown in Fig. 1.1. Fig. 1.1 Heat loss for such experiments are significant but can be taken into account by using the data collected from an initial experiment. To determine the standard enthalpy change of combustion for ethyl ethanoate (Mr = 88.0), an initial experiment, Experiment 1, was carried out using methyl ethanoate (Mr = 74.0). Experiment 1 Methyl ethanoate was combusted in a spirit burner which heated 300 g of water in a copper can as shown in Fig. 1.1 . It was found that 0.980 g of methyl ethanoate was required to raise the temperature of the water in the copper can by 10.0 °C. Table 1.1 provides some relevant data for the experiment. Table 1.1 mass / g heat capacity / J g−1 K−1 water 300 4.18 copper can 250 0.384 thermometer copper can 300 g water spirit burner ester

© Raffles Institution 2021 9729/02/S/21 [Turn Over 3 (i) Calculate the total heat energy gained by the water and the copper c an in Experiment 1. You may assume that the water and copper can are in thermal equilibrium with each other. [2] (ii) The theoretical standard enthalpy change of combustion of methyl ethanoate is −1592 kJ mol−1. Calculate the theoretical heat energy released by the mass of methyl ethanoate combusted in Experiment 1.