2022 EJC Prelims Paper 3 QP

© EJC [Turn Over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examination 2022 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CIVICS GROUP 2 1 – INDEX NUMBER CHEMISTRY Paper 3 Free Response 9729/03 21 September 2022 2 hours Candidates answer on the Question Paper Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, civics group and registration number on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. If additional space is required, you should use the pages at the end of this booklet. The question number must be clearly shown. Section A Answer all questions. Section B Answer one question. A Data Booklet is provided. The use of an approved scientific calculator is expected, where appropriate. 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 Section A 1 / 20 2 / 20 3 / 20 Section B 4 / 20 5 / 20 Total / 80 This document consists of 32 printed pages.

2 © EJC 9729/03/J2Prelims/22 Question 1 starts on the next page.

3 © EJC 9729/03/J2MYE/22 [Turn Over Section A Answer all the questions in this section. 1 (a) Elements in Period 3 of the Periodic Table form chlorides and oxides with varying properties. (i) Equal amounts of MgCl2 and PCl5 dissolve in equal volumes of water to form solutions with pH 6.5 and 1.0 respectively. Construct two equations to account for the different pH values. [2] (ii) Explain why the first ionisation energies of aluminium and sulfur are lower than the element before it. [2] (iii) Element L is an element in Period 3. L forms a chloride with a simple molecular structure but an oxide with a giant molecular structure. Identify element L and construct an equation for the reaction of its chloride with NaOH(aq). [2] ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. .............................................................................................................................

4 © EJC 9729/03/J2Prelims/22 (b) 4-(butan-2-yl)phenol is an important intermediate in organic synthesis. It must be handled carefully as it is corrosive to the eyes and skin. 4-(butan-2-yl)phenol can be synthesised by heating phenol and butan-2-ol in the presence of acid. The mechanism of this synthesis is thought to proceed via an acid- catalysed Friedel-Crafts alkylation, where butan-2-ol is first protonated by H+, before forming a carbocation. (i) Draw the structure of the carbocation formed from intermediate X. [1] (ii) Hence, describe the mechanism for the formation of 4-(butan-2-yl)phenol from the carbocation in (b)(i) and phenol. [3] (iii) Describe a simple chemical test that could distinguish between butan-2-ol and 4-(butan-2-yl)phenol. [2] (iv) Compounds M and N are two minor products in the reaction. Briefly explain why each of them is the minor product. [2]

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