RVHS H2 CHEM P2 QP RV Prelim

River Valley High School 9647/02/PRELIM/14 2014 Preliminary Examination II RIVER VALLEY HIGH SCHOOL YEAR 6 PRELIMINARY EXAMINATION (II) CANDIDATE NAME CLASS 6 CENTRE NUMBER S INDEX NUMBER H2 CHEMISTRY 9647/02 Paper 2 Structured Questions 15 September 2014 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class, centre number and index number on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions in the space provided. A Data Booklet is provided. Do NOT write anything on it. 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. For Examiner’s Use Paper 2 Question Number 1 2 3 4 5 Total Marks 12 16 15 15 14 72 Paper 1 40 Paper 3 80 Total 192 This document consists of 20 printed pages.

2 River Valley High School 9647/02/PRELIM/14 2014 Preliminary Examination II 1 Planning (P) On a field trip to Bukit Timah Hill in Singapore, a new metal carbonate called rvium carbonate, RvCO 3, was discovered by Susie. It was found that the dissolving of rvium carbonate in water is endothermic, and that the salt is only slightly soluble. The solubility of rvium carbonate is approximately 0.25 mol dm−3 at the laboratory temperature. You are to plan an experiment to determi ne the accurate valu es of both the solubility and enthalpy change of solution of rvium carbonate at the laboratory temperature. This can be done by preparing a satura ted solution of rvium carbonate and measuring the temperature change. The concentration of carbonate ions in the saturated solution can then be determined through volumetric analysis. You may assume that you are provided with:  Solid rvium carbonate, RvCO 3;  Aqueous hydrochloric acid, HC l;  Acid −base indicators;  The apparatus and chemicals normally found in a school or college laboratory. (a) Write the balanced equation for the reaction between rvium carbonate and hydrochloric acid. .................................................................................................................... .................................................................................................................... [1] (b) Draw a well-labelled diagram to show the experimental set-up you would use to determine the temperature change during the preparation of the saturated rvium carbonate solution. [2]

3 River Valley High School 9647/02/PRELIM/14 2014 Preliminary Examination II (c) Using the information given above, y ou are required to write a plan to determine the solubility and enthalpy change of solution of rvium carbonate. You plan should include details of:  the preparation of a satura ted rvium carbonate solution  the measurement of the te mperature change during the dissolution process  the intended concentration of the standard hydrochloric acid solution to be used  the titration of the saturated rvium carbonate solution with the standard hydrochloric acid solution .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... ....................................................................................................................

4 River Valley High School 9647/02/PRELIM/14 2014 Preliminary Examination II .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... .................................................................................................................... [6] (d) Assume that the temperature drop during the preparation of V cm 3 of saturated rvium carbonate solution was ∆T °C. When a 25.0 cm 3 sample of the saturated rvium carbonate so lution was titrated against a standard hydrochloric acid solution of C mol dm−3, the average titre was W cm3. Outline how you would use these results to determine the (i) solubility, in mol dm−3, of rvium carbonate; (ii) enthalpy change of solution, ∆H soln, for rvium carbonate. [3] [Total: 12]

5 River Valley High School 9647/02/PRELIM/14 2014 Preliminary Examination II 2 The halogens are a group of elements found in Group VII of the periodic table. (a) Bromine was discovered in the 1820s by Antoine-Jérôme Balard and is commonly used in halogen lamps. The halogen lamp has a tungsten filament similar to standard incandesc ent lamps. However, in addition, the halogen lamp contains a small am ount of bromine gas in the bulb that slows down the thinning of t he tungsten filament, increasing the lamp’s lifetime. When the halogen lamp is switched on, all the bromine molecules dissociate at the high temperatures and exist as single bromine atoms. Br2(g) → 2Br(g) The hot tungsten filament also evaporates and condenses on the relatively cool walls of the bulb, where it reacts with the bromine atoms to give gaseous tungsten bromide, WBr4. W(s) + 4Br(g