2024 MI PU3 MYE P4 (student)

Class Adm No Candidate Name: This question paper consists of 18 printed pages. 2024 Mid-Year Examination Pre-University 3 H2 CHEMISTRY 9729/04 Paper 4 Practical 25 June 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 in the spaces 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. 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. Question 1 2 3 4 Total Marks 15 13 12 15 55 Class Adm No

2 Answer all the questions in the spaces provided. 1 Determination of the concentration of a glucose solution using a graphical method Glucose in solution reduces purple, acidified potassium manganate( VII) solution, FA 3, to a colourless or slightly yellow solution at end-point. MnO4 + 8H+ + 5e → Mn2+ + 4H2O In this experiment, the rate of this reaction is studied by measuring the time taken for the reaction mixture to reach the end-point. You will perform a series of five experiments. Then you will graphically analyse your results to determine the order of reaction with respect to the concentration of glucose. For each experiment, you will note the time taken, t, for the reaction mixture to reach end-point. You will then calculate values of 1/t and record them to an appropriate level of precision. The experiment is then repeated using a solution of glucose of unknown concentration. By comparing the time taken for the reaction mixture to reach the end-point with the graph , the concentration of glucose in the unknown solution can be determined. FA 1 is 20% by mass of glucose solution. (i.e. there is 20 g of glucose in 100 cm3 of water) FA 2 is 1 mol dm-3 sulfuric acid, H2SO4. FA 3 is 0.0025 mol dm-3 potassium manganate(VII), KMnO4. FA 4 is a sample of glucose solution that has concentration between 30-40%. Table 1.1 Experiment volume of FA 1 /cm3 volume of water /cm3 % glucose in solution X t /s 1/t /s1 1 10.0 0.0 20% 2 8.0 16% 3 6.0 12% 4 4.0 8% 5 2.0 4% (a) Varying volumes of water are added to FA 1 to form 10 cm 3 of solution X, which contains different concentration