SRJC_H2_CHEM_P1_ANS

1 SRJC 9647/01/PRELIM/2014 Turn Over] SERANGOON JUNIOR COLLEGE General Certificate of Education Advanced Level Higher 2 Candidate Name Class CHEMISTRY 9647/01 Preliminary Examination 29 August 2014 Paper 1 Multiple Choice 1 hour Additional Materials: Data Booklet Optical Mark Sheet (OMS) READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, FIN/NRIC number and class on the OMS in the spaces provided. Shade correctly FIN/NRIC number and your class. Eg. If your NRIC is S9306660Z, shade S9306660Z for the item “index number”. There are forty questions in this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice using a soft pencil on the separate OMS. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this question paper. This document consists of 22 printed pages and 0 blank page.

2 SRJC 9647/01/PRELIM/2014 Turn Over] Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 The hydrolysis of S2Cl2 proceeds by two reactions. Reaction 1 S2Cl2 + 2H2O H2S + SO2 + 2HCl Reaction 2 2H2S + SO2 8 3 S8 + 2H2O Which of the following correctly describe the reactions? A A weakly acidic solution is formed in Reaction 1. B Reverse disproportionation occurs in Reaction 2. C The oxidation state of chlorine and oxygen changes in both reactions. D The products of Reaction 1 require 2 mol of NaOH for complete neutralisation. Ans: B  Strong acid HCl is formed.  H2S is oxidised to S 8 while SO 2 is reduced to S 8 (the reverse of disproportionation reaction).  Oxidation states of chlorine and oxygen remain as –1 and –2 in both reactions.  2HCl + 2NaOH  2NaCl + 2H2O SO2 + H2O  H2SO3 H2SO3 + 2NaOH  Na2SO3 + 2H2O Total amount of NaOH required = 4 mol 2 Sodium carbonate peroxyhydrate with the formula (Na 2CO3)x y H2O2 is used in eco-friendly cleaning products and as a laboratory source of anhydrous hydrogen peroxide. When 20.0 cm 3 of 0.100 mol dm –3 sodium carbonate peroxyhydrate is titrated with 0.200 mol dm –3 acidified KMnO 4, it requires 12.0 cm 3 of acidified KMnO 4 before the first pink colour appears. 2MnO4 – + 6H+ + 5H2O2 2Mn2+ + 8H2O + 5O2 When an identical sample is acidified, it releases 96.0 cm 3 of carbon dioxide at room conditions.

3 SRJC 9647/01/PRELIM/2014 Turn Over] 3 The successive ionisation energies, in kJ mol -1, of an elem