2024 DHS H2 Chemistry Prelim P4 (QP)

This question paper consists of 23 printed pages and 1 blank page. © DHS 2024 9729/04 [Turn over Name: Centre/Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination Year 6 H2 CHEMISTRY Paper 4 Practical Candidates answer on the Question Paper. 9729/04 19 August 2024 2 hours 30 minutes READ THESE INSTRUCTIONS FIRST Write your centre number, index number, name and class at the top of this page. 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 sci entific 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 23 and 24. 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 16 2 11 3 13 4 15 Total 55

2 © DHS 2024 9729/04 Answer all questions in the spaces provided. 1 Determination of the enthalpy change of decomposition of magnesium carbonate The enthalpy change of decomposition of magnesium carbonate, H1, cannot be determined experimentally. Reaction 1 MgCO3(s) → MgO(s) + CO2(g) H1 However, the enthalpy changes for Reaction 2 and Reaction 3 can be determined experimentally as H2 and H3 respectively. Reaction 2 MgCO3(s) + H2SO4(aq) → MgSO4(aq) + H2O(l) + CO2(g) H2 Reaction 3 MgO(s) + H2SO4(aq) → MgSO4(aq) + H2O(l) H3 You will carry out an experiment to determine the enthalpy change for Reaction 3, H3, and use this value, together with H2, to calculate the enthalpy change of decomposition of magnesium carbonate, H1.

3 © DHS 2024 9729/04 [Turn over FA 1 is solid magnesium oxide powder, MgO. FA 2 is 1.0 mol dm−3 sulfuric acid, H2SO4. (a) Determination of H3 In this experiment, you will be adding solid magnesium oxide powder to sulfuric acid in a Styrofoam cup. You will then measure the temperature of the reaction mixture over time . Plotting an appropriate graph using the data obtained will allow you to determine H3. Prepare a table in the space provided on page 4 in which to record: • all weighings to an appropriate level of precision, • all values of temperature, T, to an appropriate level of precision, • all values of time, t, recorded to 0.5 min. Procedure 1. Weigh the capped bottle containing solid FA 1. 2. Place a clean and dry Styrofoam cup on the 250 cm3 glass beaker. 3. Using a 25 cm3 measuring cylinder, add 25 cm3 of FA 2 into the Styrofoam cup. 4. Stir the solution in the cup with