JJC_H1_CHEM_P2_ANS

JURONG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 1 CANDIDATE NAME CLASS CHEMISTRY 8872/02 Paper 2 Structured 28 August 2009 2 hours Candidates answer Section A on the Question Paper Additional Materials: Answer Paper 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. A Data Booklet is provided. Do not write anything on the Data Booklet. Section A Answer all questions. Section B Answer two questions on separate answer paper. 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 Section A B5 B6 B7 Total This document consists of 11 printed pages and 1 blank page. [Turn over Page 1 of 16

Section A Answer all questions in this section in the spaces provided. 1. (a) Complete the table below. Number of Particle Electric charge Mass number Protons Electrons Neutrons X 0 32 16 16 16 Y 1- 81 35 36 46 Z 3- 70 31 28 39 [2] (b) Beams consisting of particles X, Y and Z are subjected to an electric field as shown in the diagram below. Sketch, and label, on the diagram below to show how beams of each of the three particles are affected by the electric field. [3] (c) Using the grid provided below, sketch a graph of the seven successive ionisation energies for element X. [2] [Total:7] + – X, Y, Z Y X Z Ionisation Energy / kJ mol-1 0 1 2 3 4 5 6 7 2m No. of electrons Page 2 of 16

2. (a) On heating, sodium nitrate, (NaNO 3) decomposes giving the sodium nitrite, (NaNO2) and oxygen while magnesium nitrate, (Mg(NO 3)2), decomposes giving magnesium oxide, nitrogen dioxide and oxygen. (i) Write balanced equations for the decomposition of sodium nitrate and magnesium nitrate respectively. NaNO3 → NaNO2 + ½ O2 1m Mg(NO3)2 → MgO + 2NO2 + ½ O2 1m [2] (b) (i) 5.35 g of a mixture of sodium nitrate, (NaNO3) and magnesium nitrate, (Mg(NO3)2), was heated in a fume cupboard until no more gases were evolved. The sodium nitrite, (NaNO 2), formed was dissolved in water to form a 250 cm 3 solution of nitrite ions, NO 2 . The nitrite ions in the solution reacted with 40.00 cm 3 of acidified potassium manganate(VII) solution. The nirite ion half equation is given by: NO2  + H2O NO3  + 2H+ + 2e