SRJC_H1_CHEM_P2

SRJC 2009 8872/02/PRELIM/2009 [Turn Over SERANGOON JUNIOR COLLEGE General Certificate of Education Advanced Level Higher 1 CANDIDATE NAME C L A S S CHEMISTRY 8872/02 Preliminary Examination 26 Aug 2009 Paper 2 2 hr Additional Materials: Data Booklet Answer Paper 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 work. SECTION A : Answer all questions in the space provided. SECTION B: Answer any two questions on separate answer paper. 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. For Examiner’s Use MCQ P1 /30 A1 /10 A2 /10 A3 /10 A4 /10 B5 /20 B6 /20 B7 /20 Total /110 Percentage Grade This document consists of 16 printed pages and 0 blank page

2 SRJC 2009 8872/02/PRELIM/2009 [Turn Over For Examiner’s Use 1 The industrial preparation of the polymer, poly(tetrafl uoroethene), is based on the synthesis of its monom er, tetrafluoroethene (C 2F4). Tetrafluoroethene is produced from the thermal cracking of chlorodifluoromethane (CHC lF2), as shown by the following equation: 2CHClF2(g)  C2F4(g) + 2HCl(g) (a) Use relevant data from the Data Booklet to calculate the enthalpy change of the reaction. State any assumptions that you have made. [3] (b) By using your answer to (a) and the following information, H f (CHClF2(g)) = –485 kJ mol –1 Hf (HCl(g)) = –92 kJ mol –1 calculate the enthalpy change of formation of C2F4(g). [2]

3 SRJC 2009 8872/02/PRELIM/2009 ly. (c) (i) Explain the following phenomenon: Chlorine can react w ith oxygen to form C lO─, C lO2 ─, C lO3 ─ and C l2O7 but fluorine can react with oxygen to form OF2 on (ii) Predict, with reasoning, the shape of OF 2. (iii) Predict, with reasoning, the solubility of OF2 in CCl4. [5] [Total: 10] For Examiner’s Use [Turn Over

4 SRJC 2009 8872/02/PRELIM/2009 For Examiner’s Use 2 (a) 2-bromopropane can react with sodium hy droxide in two different ways depending on conditions to give two different products A and B. CH3CHBrCH3 C3H6 C3H8O C D A B I II NaCN H+/heat (i) Draw the ‘dot-and-cross’ diagram of NaOH. (ii) Suggest and explain the polarity of 2-bromopropane. (iii) Describe the condi