2019 JPJC Prelim H2 Chem P3 QP

 Jurong Pioneer Junior College [Turn Over NAME CLASS 18S JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2019 CHEMISTRY 9729/03 Higher 2 Paper 3 Free Response 23 September 2019 2 hours Candidates answer on separate paper. Additional Materials: Answer Paper Cover Page for Answer Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class and exam index number on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a HB pencil for any diagrams, graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Section B Answer one question. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. 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. This document consists of 14 printed pages.

2  Jurong Pioneer Junior College 9729/03/J2 PRELIMINARY EXAM/2019 Section A Answer all the questions in this section. 1 (a) When a redhot wire is plunged into separate samples of the gaseous HCl and HI, a colour change was observed in one of the samples. Suggest which sample gave the colour change. Use data from the Data Booklet to explain your answer. [2] (b) Chlorine gas can be prepared by reacting concentrated hydrochloric acid with manganese(IV) oxide. Manganese (II) chloride a nd water are also formed. Chlorine gas evolved is passed through a drying agent. (i) Write an ion electron equation for the reduction of manganese (IV) oxide, MnO2. [1] (ii) The standard reduction potential, E, of the half–reaction in (b)(i) is +1.23 V. Calculate G, in kJ mol 1, for the overall reaction and use it to explain why the reaction is unlikely to occur. [3] (iii) Give two possible reasons why the reaction does occur. Explain your answer. [2] (c) Alkenes or alcohols can react with gaseous HCl to form alkyl chlorides. However, carboxylic acids do not react with gaseous HCl. (i) Describe the mechanism for the reaction of propene with HCl. [2] (ii) With reference to your mechanism in (c)(i), suggest how propene can act as a BronstedLowry base. [1] (iii) State the type of reaction that occurs between ethanol and gaseous HCl. [1] (iv) Explain why ethanoic acid does not react with gaseous HCl. [1]

3  Jurong Pioneer Junior College 9729/03/J2 PRELIMINARY EXAM/2019 [Turn Over (d) HCl can be used to prepare perchloric acid, HClO4. In the presence of HC lO4, alcohols reacts with nitriles to form N–alkylamides. This is known as the Ritter reaction, as shown in Fig. 1.1. Fig. 1.1 Consider the following reaction which employs the Ritter reaction in the last step. Fig. 1.2 Suggest appropriate reagents and conditions necessary for step s