Copy of CHIJ 2024 Sec 4E Chemistry Prelim P3

CHIJSec/2024/OLevelPrelim/6092/03 CONVENT OF THE HOLY INFANT JESUS SECONDARY Preliminary Examination in preparation for the General Certificate of Education Ordinary Level 2024 CANDIDATE NAME CLASS REGISTER NUMBER CHEMISTRY Paper 3 Practical Candidates answer on the question Paper. Additional Materials: As listed in the confidential instructions 6092/03 15 August 2024 1 hour 50 minutes READ THESE INSTRUCTIONS FIRST Write your class, register number and name in the spaces on top of this page. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use paper clips, glue or correction fluid. Answer all questions in the spaces provided. The use of an approved scientific calculator is expected, where appropriate. You should show the essential steps in any calculations and record experimental results. Qualitative analysis notes are printed on page 10. 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 2 3 Total This document consists of 10 printed pages and 2 blank pages. O

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3 [Turn over CHIJSec/2024/OLevelPrelim/6092/03 1 Hydrated potassium carbonate forms crystals of formula K2CO3•xH2O. You are going to determine the value of x in the formula K 2CO3•xH2O by titration with dilute hydrochloric acid. K2CO3•xH2O + 2HCl → 2KCl + (x+1)H2O + CO2 Read all the instructions below carefully before starting the experiment in Question 1. Instructions P is a solution containing 8.00 g of K2CO3•xH2O in 1.00 dm3 of solution. Q is 0.100 mol/dm3 hydrochloric acid. (a) (i) Put Q into the burette. Pipette 25.0 cm3 of P into a conical flask. Add a few drops of methyl orange indicator to the solution in the conical flask. Add Q from the burette, swirling the flask constantly, until the end-point is reached. Record your titration results in the space provided. Repeat the titration as many times as you consider necessary to achieve consistent results. Results [5] (ii) From your titration results, obtain an average volume of Q used. Show clearly how you obtained this volume. average volume of Q ………………………. cm3 [1]

4 CHIJSec/2024/OLevelPrelim/6092/03 (b) Q is 0.100 mol/dm3 hydrochloric acid. Using your results from (a), calculate the amount, in mol, of potassium carbonate in 25.0 cm3 of P. amount of potassium carbonate in 25.0 cm3 of P ………………………. mol [2] (c) Using your answer from (b), calculate the amount , in mol, of potassium carbonate in 1.00 dm3 of P. amount of potassium carbonate in 1.00 dm3 of P ………………………. mol [1] (d) (i) Usi