EJC 2022 Prelims Paper 4 QP and Ans

© EJC 9729/04/J2Prelim/22 [Turn Over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examination 2022 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CIVICS GROUP 2 1 – INDEX NUMBER CHEMISTRY Paper 4 Practical 9729/04 30 August 2022 2 hour 30 minutes Candidates answer on the Question Paper. Additional Materials: As listed in the Confidental Instructions READ THESE INSTRUCTIONS FIRST Write your name, civics group and registration number on 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 paper clips, highlighters, 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. 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 / 18 2 / 18 3 / 11 4 / 8 Total / 55 This document consists of 17 printed pages and 3 blank pages.

2 © EJC 9729/04/J2Prelim/22 Answer all the questions in the spaces provided. 1 To determine the percentage by mass of Fe(NO3)2 in a salt mixture FA 1 is a solution containing a salt mixture of two different ionic compounds. One of the compound is Fe(NO3)2. The other compound, X, contains a cation and an anion. In this question, you will determine the percentage by mass of Fe(NO3)2 in the mixture by preparing a diluted solution of FA 1 and carry out a titration using potassium manganate(VII). The iron(II) ions, Fe2+, are oxidised by the manganate(VII) ions, MnO4–. equation 1 5Fe2+(aq) + MnO4–(aq) + 8H+(aq) → 5Fe3+(aq) + Mn2+(aq) + 4H2O(l) The end-point of the titration occurs when the presence of unreacted MnO 4− causes the colour of the solution to become pale pink. The following reagents are provided. FA 1 is a solution containing 90.0 g dm−3 of the salt mixture in sulfuric acid FA 2 is 0.010 mol dm–3 manganate(VII) ions, MnO4– FA 3 is 1 mol dm–3 sulfuric acid, H2SO4 (a) Determining the percentage by mass of Fe(NO3)2 1. Fill a burette with FA 2. 2. Use a pipette to transfer 25.0 cm3 of FA 1 into a 250 cm3 volumetric flask. 3. Make up to the mark with deionised water and label this solution FA 4. Shake to obtain a homogeneous solution. 4. Pipette 25.0 cm3 of FA 4 into a 250 cm3 conical flask. 5. Use the 25.0 cm3 measuring cylinder to add 25.0 cm3 of FA 3 into the conical flask. 6. Run FA 2 from the burette into the conical flask . The end-point is reached when the solution changes colour from yellow to pale pink. 7. Record your titration results in the space on the next p