CJC_H2_CHEM_P2 Prelim

CATHOLIC JUNIOR COLLEGE Preliminary Examination 2009 Higher 2 CANDIDATE NAME CLASS CHEMISTRY 9746/02 Paper 2 Structured Questions 4 September 2009 1 hour 30 minutes 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. 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. This document consists of 11 printed pages and 1 blank page. CJC Chemistry Department © CJC 2009 For Examiner’s Use 1 2 3 4 5 Total 2 T

 CJC 2009 9746/02/prelim/09 2 second ionisation energy Na Mg Al Si P S C l Ar 1 (a) The second ionisation energies of the elements in Period 3 are given in the graph below. (i) Define, by means of an equation, what is mean t by the second ionisation energy of magnesium. …………………………………………………………… …………… ……………… ...……....... (ii) Explain why the second ionisation energy of silicon is lower than that of aluminium. …………………………………………………………… …………… ……………… ...……....... …………………………………………………………… …………… ……………… ...……....... …………………………………………………………… …………… ……………… ...……....... [2] (b) Orange street lamps contain sodium metal with a sma ll amount of neon gas. The light is produced when gaseous atoms are ionised in an elect ric field. When first turned on, the lamps emit a red glow characteristic of neon but, a fter a time, the orange glow of sodium predominates. Suggest a brief explanation of this phenomenon. …..……………… …………………………………………… …………… ……………… ...……....... …..…………………………………………………………… …………… ……………… ...……....... …..…………………………………………………………… …………… ……………… ...……....... …..…………………………………………………………… …………… ……………… ...……....... [2] (c) The behaviours of the oxides and chlorides of alumi nium and silicon with water are similar, but for different reasons. Explain as fully as you can, giving balanced equa tions where relevant, why (i) aluminium oxide and silicon dioxide are both insoluble in water, and …………………………………………………… ……… …………… ……………… ...……....... …………………………………………………………… …………… ……………… ...……....... …………………………………………………………… …………… ……………… ...…….......

 CJC 2009 9746/02/prelim/09 3 (ii) aluminium chloride and silicon tetrachloride both react with water to give acidic solutions. ………………………………………………………… ……………… ……………… ...……....... …………………………………………………………… …………… ……………… ...……....... …………………………………………………………… …………… ……………… .