RI_H1_CHEM_P2_QP

1 Raffles Institution 2015 8872/02/S/15 [Turn Over RAFFLES INSTITUTION 2015 YEAR 6 PRELIMINARY EXAMINATION Higher 1 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 8872/02 Paper 2 Structured Questions 15 September 2015 2 hours Candidates answer Section A on the Question Paper. Additional Materials: Answer paper Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces provided at the top of this page. Write in dark blue or black pen in the spaces provided. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all the questions on the question paper. Section B Answer two questions on separate answer paper. A Data Booklet is provided. Do not write anything on it. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Paper 1 / 30 Paper 2 (circle the questions you have answered) A1 / 15 A2 / 10 A3 / 15 B4 / 20 B5 / 20 B6 / 20 / 80 Total This document consists of 13 printed pages.

2 Raffles Institution 2014 8872/02/S/14 [Turn Over Section A (40 marks) 1 (a) Dinitrogen pentoxide, N2O5, decomposes to NO2 and O2 at relatively low temperatures according to the following equation: 2N2O5(org)  4NO2(org) + O2(g) A student investigated the rate of decomposition of N 2O5 and carried out the reaction in a CC l4 solution at 45 °C. The total volume of gas liberated was recorded every minute. The results are tabulated below. time/ min 0 1 2 3 4 5 6 7 ∞ total volume of gas/ cm3 0 23.0 36.5 46.0 51.0 54.5 57.0 58.5 59.0 (i) Plot the experimental results on the grid below.

3 Raffles Institution 2015 8872/02/S/15 [Turn Over (ii) Explain what is meant by the term overall order of reaction. ........................................................................................................................................ ........................................................................................................................................ (iii) Explain, as fully as you can, why the experimental results indicate that the overall kinetics are first order, and hence write the rate equation. ........................................................................................................................................ .................................................................