Copy of PLMGSS 2024 4E Chem P3 QP

1 CANDIDATE NAME CLASS CLASS INDEX NO CENTRE NUMBER S INDEX NUMBER CHEMISTRY 6092/03 Paper 3 Practical 23 August 2024 Redox Reactions, Moles, Rates of Reactions, Energy Changes 1 hour 50 minutes READ THESE INSTRUCTIONS FIRST Write your name, class, class index number, centre number and O level index number on all the cover 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 a soft 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 page 11. At the end of the examination, fasten all your work securely together, if applicable. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 11 printed pages. Shift Laboratory For Examiner’s Use 1 /18 2 /12 3 /10 Total /40 Paya Lebar Methodist Girls’ School (Secondary) Preliminary Examination 2024 Secondary 4 Express / G3 [Turn Over

2 1 Some cleaning products contain a solution of sulfamic acid. You are going to determine the concentration of sulfamic acid in a sample of a cleaning product by titration with sodium hydroxide. The sulfamic acid can be represented by the formula, HA. The equation for the reaction occurring in the titration is shown. HA + NaOH → NaA + H2O Read all the instructions below carefully before starting the experiment in Question 1. Instructions P is 0.200 mol / dm3 sodium hydroxide. Q contains aqueous sulfamic acid. The solution was made by diluting a sample of 100 cm3 of the cleaning product to 1.00 dm3 by adding deionised water. T is thymolphthalein indicator. (a) (i) Fill the burette with P. Use the pipette to transfer 25.0 cm3 of Q into a conical flask. Add a few drops of the thymolphthalein indicator, T, to the solution in the conical flask. Ensure the lid is placed back on the container of T after use. Add P from the burette, swirling the flask constantly. At the end-point, one drop of P produces a blue colour that does not disappear on swirling. Record your titration results in the space provided. Repeat the titration as many times as you consider necessary to achieve consistent results. Results [5]

3 (ii) From your titration results, obtain an average volume of P to be used in