MI_Prelim 2008 H2 Chemistry Paper 3

Class Adm No Candidate Name: This question paper consists of 11 printed pages. [Turn over Preliminary Examinations 2008 Pre-university 3 H2 CHEMISTRY 9746 / 03 Thursday 11 Sep 2008 2h Additional materials: Foolscap Paper Data Booklet READ THESE INSTRUCTIONS FIRST 1. Do not turn over this question paper until you are told to do so. 2. Write your name, class and index number in the spaces provided at the top of this page and on all the work you hand in. 3. Write in dark blue or black pen on both sides of the paper. 4. You may use a soft pencil for any diagrams or graphs. 5. DO NOT use staples, paper clips, highlighters, glue or correction fluid or tape. 6. Answer FOUR out of five questions. 7. Give non-exact numerical answers correct to 3 significant figures , or 1 decimal place in the case of Mr and Ar, unless a different level of accuracy is specified in the question. 8. The number of marks is given in brackets [ ] at the end of each question or part question. 9. You are reminded of the need for good English and clear presentation in your answers and to show all working in calculations. 10. The use of a calculator is expected, where appropriate.

1. This question explores the physical and c hemical properties of various types of halogen-containing compounds. (a) (i) By considering the structure and bonding in each compound, explain why potassium chloride and silicon (IV) chloride shows a marked difference in their melting points. (ii) State what is observed when separate samples of potassium chloride and silicon (IV) chloride are added to water. Write equation(s) for the reaction(s) which occur and, in each case, state the approximate pH of the solution formed. [4] (a) Potassium chloride and potassium bromide are white solids which dissolve in water to form colourless solutions. To distinguish the above compounds, often silver nitrate solution is used, leading to the formation of white silver chloride and cream silver bromide precipitates. Suggest an alternative chemical test to distinguish the two compounds. State clearly what will be observed for both compounds and write balanced equations for any reactions that occur. [4] (c) A solution containing 1.0 x 10 -4 mol dm-3 of Ag+ ions is slowly stirred into an equal volume of solution which contains KCl and KBr, each with the same concentration of 1.0 x 10-4 mol dm-3. The numerical values of the solubility products are: K sp (AgCl) = 1.8 x 10-10 Ksp (AgBr) = 3.3 x 10-13 Show with clear workings, what will be observed from above. [3] 2

(b) CH3Cl can form (CH3)2NH when reacted with an excess of CH3NH2. (i) Outline a mechanism to show the production of (CH 3)2NH. (ii) Draw the structural formula of two other possible compounds produced in the reaction. [5] (c) CH 3Cl can also react with phenol under various