MJC_H2_CHEM_P3

No part of this paper should be repro duced for commercial use without the prior written permission of Meridian Junior College. Class Reg Number Candidate Name _____________________________ Meridian Junior College 2009 JC 2 Preliminary Examination H2 Chemistry 9746 14 September 2009 2 hours Paper 3 Free Response Additional Materials Data Booklet Writing paper INSTRUCTION TO CANDIDATES Write your name, class and regi ster number in the spaces pr ovided at the top of this page. Answer any 4 out of 5 questions. Begin each question on a fresh page of writing paper. Fasten the writing pa pers behind the given Cover Page for Questions 1 & 2 and Cover Page for Questions 3, 4 & 5 respectively. Hand in Questions 1 & 2 and 3, 4 & 5 separately. You are advised to spend about 30 min per question only. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. You are reminded of the need for good English and clear presentation in your answers. This question paper consists of 15 printed pages. ©chemistry department@ meridian jc 1

Answer any 4 out of 5 questions in this paper. Begin each question on a fresh page of writing paper. 1 Sulphuryl chloride, SO 2Cl2, is often used as a source of C l2 for various organic reactions. Sulphuryl chloride is also a highly reactive gaseous compound. When heated, it decomposes endothermically as follows: SO2Cl2(g) SO 2(g) + Cl2(g) A 7:2 mole ratio of SO 2Cl2 and C l2 is placed in an evacuated vessel at 375 K and 6 atm. After 10 minutes, the mixtur e reached equilibrium and the partial pressure of SO2 is found to be 0.625 atm. (a) Write an expression for the equilibrium constant, Kp, and calculate its value. [3] (b) Suggest, with a reason, how the position of equilibrium might alter when the temperature is increased at the 20th minute. Hence, draw labelled sketches on the same graph to show how the number of moles of sulphuryl chloride and sulphur dioxide gas would change from the start of the decomposition till the new equilibrium is reached. [3] (c) Sulphuryl chloride is commonly c onfused with thionyl chloride, SOC l2. Equimolar amounts of SOC l2 and SO2Cl2 are added separately to wa ter to yield an acidic solution with the evolution of some white fumes. Suggest, with the aid of suitable equat ions, which compound would yield a solution with a lower pH value. [2] (d) Sulphuryl chloride is a very good source of C l2. Propene undergoes free radical substitution with sulphuryl chloride to give 3-chloroprop-1-ene. (i) Name the type of hybridisation that is present in the carbon atom