2024 XMS P3 PRELIM QP

This document consists of 10 printed pages. XINMIN SECONDARY SCHOOL SEKOLAH MENENGAH XINMIN Preliminary Examination 2024 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY Secondary 4 Express Setter: Mr Lim Boon Ping Vetters: Mrs Annie Ng / Ms Tiffany Lim 6092/03 14 Aug 2024 1 hour 50 minutes Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions READ THESE INSTRUCTIONS FIRST Write your name, class and index number on the work you hand in. 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, correction fluid or highlighters. 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. Answer all questions in the spaces provided on the Question Paper. Qualitative Analysis Notes are printed on page 9. 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 16 2 18 3 6 Total 40 Parent’s Signature Shift Laboratory

2 XMSS/Chemistry/6092/03/Preliminary Examination 2024 Answer all questions. Write your answers in the spaces provided. 1 You are going to investigate the temperature changes when two solids, C and D, dissolve in water. Read all the instructions carefully before starting the experiments in Question 1. Instructions You are going to do two experiments. (a) Experiment 1 1. Put the polystyrene cup into the 250 cm3 beaker for support. 2. Use the measuring cylinder to pour 40 cm3 of deionised water into the polystyrene cup. 3. Measure the initial temperature of the deionised water and record it in the first row of the table. 4. Add the 5 g sample of solid C to the polystyrene cup and stir the solution with the thermometer. 5. Measure and record the temperature of the solution after 1 minute. 6. Calculate and record the temperature change, including whether the temperature increased (+) or decreased (–). 7. Pour the solution away and rinse out the polystyrene cup with deionised water. 8. Repeat the procedure using the 7 g and 8 g samples of solid C. Record your results and the temperature change, including whether the temperature increased (+) or decreased (–), in the appropriate row of the table. mass of solid C / g initial temperature of the water / C temperature of the solution after 1 min / C temperature change / C 5 7 8 [2]

3 XMSS/Chemistry/6092/03/Preliminary Examination 2024 (b) Experiment 2 Repeat Experiment 1 but using the 3 g, 4 g, 6 g and 8 g samples of solid D. Record your results in a table. In your table, c alculate and record the temperature changes in each case, including whether the temperature increased (+) or decreased (–). [3] (c) Use your results for Experiments 1 and 2 to plot a graph of temperature change against mass of solid added on the grid provided in the next page. You should include the origin (0,0). Draw two straight lines of best fit and label each graph clearly.

4 XMSS/Chemistry/6092/03/Preliminary Examination 2024 [4]

5 XMSS/Chemistry/6092/03/Preliminary Examination 2024 (d) Use your graph to estimate the temperature change after 1 minute if 6 g of solid C were added to 40 cm3 of deionised water. ……………… °C [1] (e) State whether ΔH, the enthalpy change that occurs when solid C dissolves in water, has a positive or negative value. Explain your answer. ………………………………………………………………………………………..…. ………………………………………………………………………………………..…. [1] (f) Use your experimental data to suggest the temperature of the solution containing 8 g of solid D, if the solution were left for 2 hours. ……………… °C [1] (g) Suggest how the temperature changes measured after 1 minute would differ if the experiments were repeated using 80 cm 3 instead of 40 cm 3 of deionised water in each case. ………………………………………………………………………………………..…. ………………………………………………………………………………………..…. ………………………………………………………………………………………..…. [2] (h) Suggest one change you could make to the experiments to obtain more accurate results. Explain how this change would make the results more accurate. change …………………………………………………………………………………. explanation ……………………………………………………………………………. ………………………………………………………………………………………..…. ………………………………………………………………………………………..…. [2] [Total: 16]

6 XMSS/Chemistry/6092/03/Preliminary Examination 2024 2 You are provided with solutions R and S. Read all the instructions carefully before starting the experiments in Question 2. Instructions (a) Carry out the following tests. You should test and identify any gases evolved. The volumes given below are approximate and should be estimated rather than measured unless instructed otherwise. Record your observations in the table. If there are no observable changes, write ‘no observable change’. test observations Test 1 Test a sample of R with both red and blue litmus paper. Test 2 To 1 cm depth of aqueous zinc sulfate in a clean test-tube, add R slowly with mixing until no further change occurs. Test 3 To 1 cm depth of aqueous chromium(III) chloride in a clean test- tube, add R slowly with mixing until no further change occurs. Test 4 Gently warm 2 cm depth of R in a clean test-tube. Test 5 (i) To 1 cm depth of aqueous sodium chloride in a clean test-tube, add a few drops of aqueous silver nitrate. (ii) To the mixture from (i), add R until no further change occurs. Test 6 (i) To 1 cm depth of aqueous potassium iodide in a clean test-tube, add an equal volume of dilute sulfuric acid and then one or two drops of S. (ii) To the mixture from (i) add an equal volume of S and allow to stand for a few minutes.

7 XMSS/Chemistry/6092/03/Preliminary Examination 2024 test observations [15] Test 7 To 2 cm depth of acidified aqueous potassium manganate(VII) in a clean test- tube, add an equal volume of S. Test 8 (i) To 1 cm depth of aqueous iron(II) sulfate in a clean test-tube, add an equal volume of S. (ii) Add R to the mixture from (i) until no further change occurs. (b) Use the results of your tests to identify the compound present in R. ………………………………………………………………………………………..…. [1] (c) Deduce the role of S in Test 7. Explain your answer. ………………………………………………………………………………………..…. ………………………………………………………………………………………..…. ………………………………………………………………………………………..…. [2] [Total: 18]

8 XMSS/Chemistry/6092/03/Preliminary Examination 2024 3 A toothpaste contains: • sodium fluoride • calcium carbonate • silicon dioxide • a mint flavouring soluble in water Plan an investigation to find the percentage by mass of calcium carbonate and the percentage by mass of silicon dioxide in the toothpaste. In your answer, you should include the apparatus you would use and how you would calculate each percentage. You may assume that the apparatus normally found in a school laboratory is available. [Ar: Na: 23; F: 19; Ca: 40; C: 12; O: 16; Si: 28] ………………………………………………………………………………………..……….. ………………………………………………………………………………………..……….. ………………………………………………………………………………………..……….. ………………………………………………………………………………………..……….. ………………………………………………………………………………………..……….. ………………………………………………………………………………………..……