Title chem p52 qp.pdf ✅

This document has 16 pages. Any blank pages are indicated. [Turn over Cambridge International AS & A Level CHEMISTRY 9701/52 Paper 5 Planning, Analysis and Evaluation February/March 2025 1 hour 15 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● You may use a calculator. ● You should show all your working and use appropriate units. INFORMATION ● The total mark for this paper is 30. ● The number of marks for each question or part question is shown in brackets [ ]. ● The Periodic Table is printed in the question paper. ● Important values, constants and standards are printed in the question paper. *7757747323* DC (SL/CB) 340511/7 © UCLES 2025 , , * 0000800000001 * ¬O. 4mHuOaE^z5W ¬bnyVa¢a {={Jtw ¥¥¥U5 5UUE 5eUeU
2 © UCLES 2025 9701/52/F/M/25 1 Brass is an alloy of copper and zinc. An experiment is completed to find the percentage by mass of copper in a sample of brass. In the experiment, the sample of brass is reacted with an excess of concentrated nitric acid, HNO3 . This forms a solution containing Cu2+(aq) ions. The amount of Cu2+(aq) ions formed is determined by titration. A student uses the following method. step 1 Weigh a glass beaker and record the mass. step 2 Add approximately 1.00g of powdered brass to the beaker and record the mass of the beaker and the brass. step 3 Transfer the brass into conical flask A which contains excess concentrated HNO3 . step 4 Reweigh the glass beaker and record the mass. step 5 Add aqueous sodium carbonate, Na2CO3 (aq), dropwise to flask A until a precipitate of copper(II) carbonate, CuCO3 (s), appears. Then add dilute ethanoic acid dropwise until the precipitate is fully dissolved. step 6 Transfer all the contents of flask A to a 100.0cm3 volumetric flask and make up to the mark with distilled water. This is solution B. step 7 Transfer 10.0cm3 of solution B into conical flask C. step 8 Add 10cm3 , an excess, of aqueous potassium iodide, KI(aq), to flask C. step 9 Titrate the contents of flask C against 0.0600moldm–3 sodium thiosulfate, Na2 S2O3 (aq), using starch solution as an indicator. step 10 Repeat steps 7 to 9 until concordant results are obtained. * 0000800000002 * , , ĬÍĊ®Ġ ́íÈõÏĪÅĊßü·þ× Ĭâðú×ĞęĈÚüýâ°āúÌïĂ ĥμõÕõõÅÕĥĕĕÅąõÅĕąÕ DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN
3 © UCLES 2025 9701/52/F/M/25 [Turn over (a) Both copper and zinc in brass react with concentrated HNO3 in step 3. reaction 1 Zn(s) + 4HNO3 (aq) Zn(NO3 ) 2 (aq) + 2NO2 (g) + 2H2O(l) reaction 2 Cu(s) + 4HNO3 (aq) Cu(NO3 ) 2 (aq) + 2NO2 (g) + 2H2O(l) Suggest why step 3 in the experiment should be completed in a fume cupboard. ............................................................................................................................................. [1] (b) Explain why the glass beaker is reweighed in step 4. ................................................................................................................................................... ............................................................................................................................................. [1] (c) Name a suitable piece of apparatus to transfer the 10.0cm3 of solution B in step 7. ............................................................................................................................................. [1] (d) Identify the substance used to rinse the burette before step 9 is done for the first time. ............................................................................................................................................. [1] (e) In step 9, 0.0600moldm–3 Na2 S2O3 (aq) is used. This solution is prepared from 0.200moldm–3 Na2 S2O3 (aq) before the experiment. Describe how to make a 100.0cm3 standard solution of 0.0600moldm–3 Na2 S2O3 (aq) from the 0.200moldm–3 Na2 S2O3 (aq) solution. Give the name and capacity of any apparatus you would use. Write your answer in a series of numbered steps. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [3] * 0000800000003 * , , ĬÏĊ®Ġ ́íÈõÏĪÅĊßú·þ× ĬâïùÏĬĕøßþôħĬùÞÌÿĂ ĥμąĕμĕåμõĥÅÅąĕåÕĕÕ DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN