2023 ASRJC H2 Chem Prelim P3 QP

ASRJC JC2 PRELIM 2023 9729/03/H2 [Turn over ANDERSON SERANGOON JUNIOR COLLEGE 2023 JC 2 PRELIMINARY EXAMINATION NAME:______________________________ ( ) CLASS: 23 / _____ CHEMISTRY 9729/03 Paper 3 Free Response Questions 18 September 2023 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class and register 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 Paper 3 A1 / 15 Paper 1 (15%) / 30 A2 / 22 Paper 2 (30%) / 75 A3 / 23 Paper 3 (35%) / 80 B4* / 20 Paper 4 (20%) / 55 B5* / 20 Percentage *Circle the question you have attempted Grade This document consists of 32 printed pages.

2 ASRJC JC2 PRELIM 2023 9729/03/H2 Section A Answer all the questions in this section. 1 (a) (i) Describe and explain the relative basicities of methylamine, dimethylamine and trimethylamine in the gas phase. [3] (ii) Explain why amides are neutral. [1] ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ……………………………………………………………………………………………...… ……………………………………………………………………………………………...… ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………...

3 ASRJC JC2 PRELIM 2023 9729/03/H2 [Turn over (b) Deuterium (symbol D or 2 1H ) was discovered in 1931. Deuterium accounts for 0.0156% of all the naturally occurring hydrogen in the oceans, while the most common isotope 1 1H accounts for 99.98%. Tritium (symbol T or 3 1H ), a rare and radioactive isotope of hydrogen account for only 0.0044%. Chemically, deuterium behaves similarly to ordinary hydrogen. (i) Calculate the average Ar of hydrogen. Give your answer to four decimal places. [1] (ii) On the same diagram, sketch how a beam of singly positively charged deuterium ions and a beam of hydrogen ions will behave in an electric field. In your diagram, indicate clearly the relative angle of deflection for each beam. (You may let the angle of deflection of hydrogen ions be x°) [2] (iii) Explain the difference in the thermal stability of DCl, DBr and DI. [2] ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………...

4 ASRJC JC2 PRELIM 2023 9729/03/H2 (c) Deuterium can replace the normal hydrogen in water molecules to form heavy water, D2O. Some data of light water and heavy water are given in Table 1.1. Table 1.1 Property D2O (Heavy water) H2O (Light water) Freezing point (oC) 3.82 0.00 Boiling point (oC) 101.4 100.0 Density at standard temperature and pressure (g cm–3) 1.106 (solid) 0.998 (solid) (i) Suggest if distillation is effective in separating heavy water from light water. [1] (ii) Using Table 1.1, suggest with reasoning, how a scientist can differentiate the two types of water without the use of a temperature measuring device. (Density of liquid light water is 1.0 g cm–3) [2] ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………...

5 ASRJC JC2 PRELIM 2023 9729/03/H2 [Turn over (d) Deuterated solvents (such as D2O) are a group of compounds where one or more hydrogen atoms are substituted by deuterium atoms. It may be assumed that they have similar chemical reactivity as their hydrogen analogues. (i) D2O is added to 3-chloropropionyl chloride. C1 C Cl H H H H C2 O Cl 3-chloropropionyl chloride Comment on the reactivity of C 1 and C2 and write a balanced chemical equation for the reaction. [2] (ii) Construct a balanced chemical equation to show how deuterated ethanol, C2D5OD, reacts with ethanoic acid, CH3CO2H in the presence of acid catalyst. [1] ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... …………………………………………………………