MJC_H2_CHEM_P3 ANS Prelim

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 Answers 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 register number in the spaces provided 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

1 (a) 22 22 () ( ) 1.958 x 0.625 = ( ) 4.042 SO Cl p SO Cl PPK P = 0.303 atm (b) The equilibrium position will shift ri ght towards the endothermic reaction to absorb heat. 0 SO2 SO2 SO2Cl2 SO2Cl2 Time 10 mins 20 mins (c) SOCl2 + H2O SO2 + 2HCl SO2Cl2 + 2H2O H2SO4 + 2HCl  SO 2Cl2 in water yields 3 mol of strong acid in comparison to 2 mole strong acid for SOCl2hence pH is lower. (di) sp 2 hydrisation [1] three sp2 orbitals (ii) Homolytic fission is the breaking of a co valent bond such that each atom retain s only one of the shared electrons. HO + SO2Cl2  HOCl + SO2 + Cl ©chemistry department@meridian jc 2

©chemistry department@meridian jc 3 CH2=CHCH2Cl CH2(Cl) (OH)CH CH 2Cl CH )CH( OH)CH2(CN CN2 CH )CH(OH) CH step 1 step 3 step 2 (iii) 2(COOH 2COOH Step 1: aqueous Br2 or Cl2 Step 2: alcoholic KCN, heat Step 3: aq HCl or H 2SO4, heat (iv) 1 Outline the mechanism that occu rs for the formation of either B or C. CH2Cl CCH H H Br + 2 Concept : A racemic mixture is formed due to equal probability of attack from either plane [1] [1] Br Br + - + :Br- slow CC H H H CH2Cl CH2Cl CCH H H BrBr CH2Cl CCH H H Br + fast + :Br- CH2Br C * CH2Br C* H Br CH2Cl H Br ClH2C

2a(i) Gas liberated - Chlorine gas C lO- (aq) + Cl- (aq) + H2O (l) Cl2 (g) + 2OH- (aq) (ii) Chlori