2024 MI PU3 H2 Chem EOY P4 answers (final) w EC

Class Adm No Candidate Name: This question paper consists of 19 printed pages and 1 blank page. 2024 Preliminary Examination Pre-University 3 H2 CHEMISTRY 9729/04 Paper 4 Practical 27 Sep 2024 2 hours 30 minutes Candidates answer on the Question paper. READ THESE INSTRUCTIONS FIRST Do not turn over this question paper until you are told to do so Write your name, class and admission number 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 at the back of the Question Paper. 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. Question 1 2 3 4 Total Marks 14 18 14 9 55 Shift Laboratory

2 1 Determination of enthalpy change of reaction FA 1 is solid sodium hydrogencarbonate, NaHCO3 FA 2 is 1.50 mol dm-3 sulfuric acid, H2SO4 (also required in both question 2 and 3) Sodium hydrogencarbonate is commonly known as baking soda and is used as a reagent in various reactions. It is soluble in water according to equation 1. equation 1 NaHCO3(s) + aq ⟶ Na+(aq) + HCO3–(aq) H1 It can also react with acids in both solid and aqueous state. equation 2 2NaHCO3(s) + H2SO4(aq) ⟶ Na2SO4(aq) + 2H2O(l) + 2CO2(g) H2 equation 3 2NaHCO3(aq) + H2SO4(aq) ⟶ Na2SO4(aq) + 2H2O(l) + 2CO2(g) H3 In this question, you will carry out experiments to determine H1 and H2, then use Hess’s Law to determine H3. For Examiners’ Use (a) In this experiment, you will determine the maximum temperature change when a known mass of solid sodium hydrogencarbonate, FA 1, reacts with sulfuric acid, FA 2. Then, you will determine H2. In an appropriate format in the space provided below, record  all weighings to an appropriate level of precision,  all values of temperature to an appropriate level of precision. Procedure 1. Weigh the capped bottle containing FA 1. 2. Place one polystyrene cup inside a second polystyrene cup. Place these in a glass beaker to prevent them from tipping over. 3. Use a measuring cylinder to transfer 25 cm3 of FA 2 into the first polystyrene cup. Cover the cup with the lid provided. 4. Stir FA 2 in the cup gently with the thermometer. Read and record its temperature. 5. Transfer all the FA 1 to the polystyrene cup. Stir the mixture.