2019 HCI Prelim H2 Chem P4 QP

This document consists of 18 printed pages. HWA CHONG INSTITUTION C2 Preliminary Examination Higher 2 NAME CT GROUP 18S CHEMISTRY Paper 4 Practical Candidates answer on the Question Paper 9729/04 28 August 2019 2 hours 30 minutes READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Give details of the practical shift and laboratory where appropriate, in the boxes provided. 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. You may lose marks if you do not show your working or if you do not use appropriate units. Qualitative Analysis Notes are printed on pages 17 and 18. 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. Shift Laboratory For Examiner’s Use 1 2 3 4 Total

2 © Hwa Chong Institution 2019 9729 / 04 / C2 Prelim 2019 Answer all the questions in the spaces provided. 1 Determination of the enthalpy change of neutralisation, Hneut, of a strong acid by a strong base The enthalpy change of neutralisation, Hneut, is the enthalpy change when one mole of water is formed during a neutralisation reaction as shown in equation 1. equation 1 H+(aq) + OH−(aq)  H2O(l) FA 1 is a solution of sulfuric acid, H2SO4 FA 2 is 1.50 mol dm–3 sodium hydroxide, NaOH You will perform a series of experiments using different volumes of FA 1 and FA 2 which together give a total volume of 50 cm3. The change in temperature, T, for each experiment will be determined and used to plot a graph of T against volume of FA 1 used. You will then use data from the graph to determine the concentration of sulfuric acid in FA 1, and a value for the enthalpy change of neutralisation, Hneut. (a) (i) Determining the change in temperature for a series of reactions between FA 1 and FA 2 1. Place the Styrofoam cup in a 250 cm3 beaker to prevent it from tipping over. Use a measuring cylinder to transfer 10.0 cm3 of FA 1 into the cup. 2 Use a measuring cylinder to measure 40.0 cm3 of FA 2. 3. Measure the temperature of the FA 1 solution using the thermometer. Record the initial temperature of FA 1 as TFA1. 4. Add FA 2 to FA 1 in the Styrofoam cup. Stir the mixture using the thermometer and record the maximum temperature, Tmax, reached. 5. Wash and dry the Styrofoam cup. 6. Repeat steps 1 to 5 using 20.0 cm3, 25.0 cm3, 30.0 cm3, 35.0 cm3 and 40.0 cm3 of FA 1 and appropriate volumes of FA 2 each time such that the total volume of the reacting mixt