PJC_H1_CHEM_P2

PIONEER JUNIOR COLLEGE, SINGAPORE JC2 PRELIMINARY EXAMINATIONS HIGHER 1 CANDIDATE NAME CT INDEX GROUP NUMBER 8 0 CHEMISTRY 8872/02 Paper 2 Structured and Free-Response 24 September 2009 2 hours Additional Materials: Answer Paper Data Booklet READ THESE INSTRUCTONS FIRST Write your Centre number, index number and name on all 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 workings. Do not use staples, paper clips, highlighters, glue or correction fluid. 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 Paper 1 Section B B4 / 20 Marks / 30 B5 / 20 Section A B6 / 20 A1 / 17 Total A2 / 16 / 100 A3 / 7 Grade This document consists of 12 printed pages. © PJC 2009 8872/02/Prelim/S/09 [Turn over

2 Section A Answer all the questions in this section in the spaces provided. 1 This question is about aluminium, an elem ent in the third peri od of the Periodic Table. (a) (i) On the grid below, sketch the trend of the first ionisation energies of elements of Period 3 from sodium to argon. (ii) Write an equation for the first ionisation energy of aluminium. (iii) Explain why the first ionisation ener gy of aluminium is lower than magnesium. [3] (b) A beam of particles of 27Al+ and 9Be+ is passed through an electric field. If the angle of deflection of the 27Al+ particle is 3o, state the angle of deflection for the 9Be+ particle. [1] For Examiner’s Use first ionisation energy / kJ mol -1 element Na Mg Al Si P S Cl Ar © PJC 2009 8872/02/Prelim/S/09 [Turn over

3 A lCl3 is a covalent compound that exists as a white solid at room temperature and pressure. When A lCl3 is heated to a sufficiently high temperature, it sublimes to gives the Al2Cl6 dimer. (c) Draw a dot-and-cross diagram for the A l2Cl6 dimer. Name the type of bond responsible for the formation of the dimer. Type of bond: ______ _______________________________ [2] (d) 2.0 mol of gaseous A lCl 3 is heated at 800 K in a 750 cm 3 vessel. When dynamic equilibrium is achieved, 0.971 mol of gaseous Al 2Cl6 is formed in the vessel. (i) Define the term dynamic equilibrium. (ii) Write a balanced equati on for the equilibrium. (iii) Calculate the value and state the units of the equilibrium constant, K c, for this reaction at 800 K. [5] For Examiner’s Use © PJC 2009 8872/02/Prelim/S/09 [Turn over

4 (e) AlCl3 dissolves in water to give a