DHS_H2_CHEM_P2 Prelim

_______________________________________________________________________________________________ This question paper consists of 18 printed pages and 0 blank page. © DHS 2011 [Turn over Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination Year 6 H2 CHEMISTRY 9647/02 Paper 2 Structured 21 September 2011 2 hours Additional Materials: Data Booklet INSTRUCTIONS TO CANDIDATES 1 Write your name, index number and class on this cover page. 2 Answer all questions. 3 Write your answers in the spaces provided on the question paper. 4 A Data Booklet is provided. 5 The number of marks is given in brackets [ ] at the end of each question or part question. 6 You may use a calculator. FOR EXAMINER’S USE Question No. 1 2 3 4 5 6 Total % Marks 12 14 15 11 11 9 [72]

2 © DHS 2011 9647/02 [Turn over Answer all questions in the space provided. 1 Planning When aqueous sodium chloride, NaC l, is added to aqueous lead( II) nitrate, Pb(NO 3)2, a white precipitate of lead chloride, PbCl2, is produced. A suggested stoichiometric equation is Pb(NO3)2(aq) + 2NaCl(aq)  PbCl2(s) + 2NaNO3(aq) In separate experiments, different volumes of 0.20 mol dm –3 aqueous sodium chloride are added to a fixed volume of 0.10 mol dm –3 aqueous lead( II) nitrate. In each case, the precipitate, PbCl2 will be formed. This precipitate is then filtered, washed with distilled water and thoroughly dried. The mass of the precipitate is recorded. You are to plan an experiment to investigate this reaction in order to confirm or reject the stoichiometry of the equation. (a) (i) By considering the suggested stoichiometric equation, predict how the number of moles of the precipitate, PbC l2, will change as the number of moles of NaC l added increases. Prediction: (ii) Sketch the graph which would result if NaC l is the limiting reagent . Start your graph with no NaCl added. [2] PbCl2 /mol NaCl /mol 0

3 © DHS 2011 9647/02 [Turn over (b) You are provided with 250 cm 3 of 0.20 mol dm –3 aqueous sodium chloride and some solid lead(II) nitrate. (i) Outline how you would prepare 250 cm 3 of 0.10 mol dm –3 aqueous lead( II) nitrate. [Ar: N, 14.0; O, 16.0; Pb, 207.0] (ii) You will be carrying out five sets of experiments to obtain different masses of precipitate. Give a step by step description of how you would carry out one such experiment. You need to state only the following:  the volumes of each solution to be used,  how the volumes will be measured, and  how you would dry the precipitate. [6]

4 © DHS 2011 9647/02 [Turn over (c) In the table below  enter appropriate headings to show recorded and calculated data. The headings should include appropriate units,  enter the volumes from your plan in