DHS_H2_CHEM_P3 Prelim

This question paper consists of 9 printed pages and 1 blank page. © DHS 2011 [Turn over Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination Year 6 H2 CHEMISTRY 9647/03 Paper 3 Free–Response 12 September 2011 2 hours Additional Materials: Cover Sheet Writing Papers Data Booklet INSTRUCTIONS TO CANDIDATES 1 Write your name, register number and class on this question paper and on the Cover Sheet provided. 2 Write in dark blue or black pen on both sides of the paper. 3 You may use a soft pencil for any diagrams, graphs or rough working. 4 Do not use staples, paper clips, highlighters, glue or correction fluid. 5 Answer any four questions. 6 Start each question on a fresh sheet of paper. 7 A Data Booklet is provided. 8 You are reminded of the need for good English and clear presentation in your answers. 9 The number of marks is given in brackets [ ] at the end of each question or part question. 10 At the end of the examination: 11 Fasten all work securely together with the Cover Sheet on top. 12 Hand in the question paper separately. 13 The total marks for this paper is 80 marks.

2 © DHS 2011 9647/03 [Turn over Answer any four questions. 1 Iron is the cheapest and one of the most abundant of all metals, comprising nearly 5.6% of the earth's crust and nearly the earth’s entire core. It exists in a wide range of oxidation states, from −2 to +6, although ferrous (Fe 2+) and ferric (Fe 3+) compounds are more common. (a) Acidic solutions containing ferrous ions are oxidised to ferric ions in air, with no precipitation seen. On the other hand, ferrous ions give a precipitate in alkaline solutions and the precipitate turns reddish–brown in air. With reference to the Data Booklet , explain the two reactions using relevant E  values, writing equations where appropriate. [4] (b) Ferric ions can catalyse the reaction between I–(aq) and S2O8 2–(aq). By considering relevant E values, describe and explain the role of the ferric ions in this reaction, writing equations where appropriate. [3] (c) Ferric chloride is an industrial scale commodity inorganic compound which is often used as catalyst in organic synthesis. One example is its use as a Lewis acid for catalysing the alkylation reaction of benzene by chlor oethane to form ethylbenzene. This reaction is similar to the reaction between benzene and chlorine. (i) (ii) (iii) (iv) Write a balanced equation for the overall reaction of chloroethane and benzene. State and outline the mechanism, with equations only, for the above reaction using ferric chloride as a catalyst. Hence, or otherwise, suggest how you would synthesise the following alcohol, 1–(3–nitrophenyl)propan–2–ol, starting from a chloroalkene and benzene as your only organic reagents. Your synthesis