NYJC_Prelim_CHEM_P2_ans

H2 Chemistry 9647/02 NYJC J2/16 PX [Turn over NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME Teachers’ Mark Scheme CLASS 1 5 INDEX NO. TUTOR CHEMISTRY 9647/02 Paper 2 Structured 14 September 2016 2 hours Candidates answer on the Question Paper 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 working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions in the spaces 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 brackets [ ] at the end of each question or part question. For Examiner’s Use 1 P /12 2 / 15 /60 3 / 6 4 / 13 5 / 6 6 / 20 This document consists of 17 printed pages and 1 blank page.

2 H2 Chemistry 9647/02 NYJC J2/16 PX For Examiner's Use Answer all questions in the spaces provided. 1 Planning (P) Baker’s yeast is a useful enzyme which can be used to catalyse the decomposition of hydrogen peroxide. H2O2  H2O + ½ O2 You are provided with Set-up apparatus:  1 x retort stand with clamp  1 x 100 cm3 conical flask  1 x L-shape glass tube connector fitted with a rubber bung  1 x rubber tubing connection  1 x gas syringe (possible capacities of 10, 20 or 100 cm3) Reagents and apparatus  100 cm3 of yeast suspension  100 cm3 of 3% (by weight) hydrogen peroxide  Distilled water  Stopwatch  All other common laboratory equipment When 8.0 cm 3 of the yeast suspension, 4.0 cm 3 of H2O2 and 18.0 cm 3 of distilled water is mixed, 10 cm3 of oxygen gas was produced in 90 s. Use the above information and the reagents provided to design an experiment to  prove first order reaction with respect to yeast by a graphical method  prove first order reaction with respect to hydrogen peroxide by a graphical method In your experiment, you should perform 4 other experimental runs to mea sure the volume of oxygen gas produced at regular intervals. The volume of yeast suspension used should be varied in all the runs while keeping volume of H2O2 constant at 4.0 cm3. In your experiment, illustrate / describe the following:  A labelled set-up for your experiment using the set-up apparatus provided  Table of volumes that you will be using in your experiment  Calculations to determine the maximum volume of oxygen gas produced in each experimental run. In your calculations, assume that the density of H2O2 is 1.00 g cm 3 and conditions are at r.t.p.  Procedure for measuring the volume of oxygen gas produced at regular intervals and use the results to find the initial rate for each run graphically  Graphical analysis i