SRJC H2 Chem 2012 Prelim P2 QP

1 SERANGOON JUNIOR COLLEGE General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CLASS CHEMISTRY 9647/02 Preliminary Examination 17 August 2012 Paper 2 Structured Questions (SPA) 2 hours Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and class 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 work. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions in the space provided. A Data Booklet is provided. At the end of the examination, fasten all your work securely together. The number of marks is given in the brackets [ ] at the end of each question or part questions. For Examiner’s Use P1 /40 P2 /72 P3 /80 GRAND /192TOTAL % GRADE For Examiner’s Use 1(P) /12 2 /8 3 /18 4 /10 5 /12 6 (P) /12 TOTAL /72 P2 This document consist of 16 printed pages and 0 blank page SRJC PRELIM 9647 P2 Turn Over]

2 SRJC PRELIM 9647 P2 Turn Over] 1 (a) Planning In the presence of hydrogen ions , bromate(V) ions, BrO 3–, oxidise bromide ions to bromine. BrO3– (aq) + 5Br – (aq) + 6H+ (aq) ¨ 3Br2 (aq) + 3H2O (l) The reaction is relatively slow and can be followed by adding aqueous phenol and the indicator methyl orange to the reaction mixture. As bromine is formed, it reacts rapidly with the phenol present until the latter is used up. The free bromine in solution now bleaches the methyl orange indicator. The initial rate of the reaction can be investigated by measuring the time taken for the methyl orange indicator to be bleached. You are to plan a series of experiments to determine the order of reaction with respect to the bromide ion. In addition to the standard apparatus present in a laboratory, you are provided with the following: FA 1 0.01 mol dm – 3 aqueous KBr. FA 2 1.0 mol dm– 3 potassium bromate(V), KBrO3. FA 3 1.0 mol dm– 3 sulfuric acid, H2SO4. Aqueous phenol containing methyl orange indicator Distilled water For Examiner’s Use (i) Complete the table below and outline, by means of a series of numbered steps, · the apparatus to be used · the experimental procedure · the measurements to be taken to collect the required data. Expt . Volume of phenol/methyl orange indicator solution / cm3 Volume of FA1 / cm3 Volume of FA2 / cm3 Volume of FA3 / cm3 Volume of distilled water / cm3 1 20.0 50.0 50.0 20.0 0.0 2 20.0 40.0 3 20.0 30.0 4 20.0 20.0 5 20.0 10.0

3 SRJC PRELIM 9647 P2 Turn Over] Outline of experiment: …………………………………………………………………………………………………….… ………………………………………………………………………………………………….…… …………………………………………………………………………………………………….… …………