JPJC Prelim 2025 Paper 3 QP H2 Chem

© Jurong Pioneer Junior College [Turn Over NAME CLASS 24S JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2025 CHEMISTRY 9729/03 Higher 2 Paper 3 Free Response 17 September 2025 2 hour Candidates answer on the Question paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces at the top of this page. Write in dark blue or black pen. You may use a 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. Write the Question number of the Question you have attempted, in the box provided below. A Data Booklet is provided. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 17 2 19 3 24 4 or 5 20 Penalty (delete accordingly) Lack 3sf in final answer –1 / NA Missing/wrong units in final ans –1 / NA Bond linkages –1 / NA Total 80 This document consists of 28 printed pages.

2 © Jurong Pioneer Junior College 9729/03/J2 PRELIMINARY EXAM/2025 Section A Answer all the questions in this section. 1 Nitrogen, a Period 2 element, forms a wide variety of compounds with diverse structures, oxidation states, and properties. These include ammonia, ammonium salts, amines, and nitrates, all of which play important roles in industry, agriculture, and the environment. For Examiner’s Use (a) The enthalpy changes involved in the formation of ionic and covalent compounds vary across the period. (i) Explain why the first ionisation energy of nitrogen is more endothermic than that of carbon and oxygen. [2] (ii) Some Period 3 elements can react with chlorine to produce chlorides, for example, NaCl and SiCl4. Describe and e xplain what happens when NaCl and SiCl4 are separately added to excess water. State the pH of the resultant mixtures and give relevant equations. [3] …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. ……………………………………………………………………………………. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. ……………………………………………………………………………………..

3 © Jurong Pioneer Junior College 9729/03/J2 PRELIMINARY EXAM/2025 [Turn Over (b) Ammonia (NH3), ammonium nitrate (NH4NO3), and ethanamide (CH3CONH2) are important compounds that can be used as fertilisers due to their high nitrogen content. Arrange these three compounds in order of increasing pH value of their aqueous solution. Explain your answer. [3] For Examiner’s Use …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. ……………………………………………………………………………………………. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. ……………………………………………………………………………………………..

4 © Jurong Pioneer Junior College 9729/03/J2 PRELIMINARY EXAM/2025 (c) Aqueous iron(III) nitrate, Fe(NO3)3(aq), is yellow in colour. For Examiner’s Use (i) Explain why the solution of iron(III) nitrate is yellow in colour. [3] (ii) Using data from the Data Booklet , predict what will be observed when aqueous iron(III) nitrate is added to potassium iodide, KI, giving a balanced equation for the reaction that occurs. [3] (iii) A sample of Fe(NO3)3(aq) was added to aqueous sodium hydroxide. A red- brown precipitate formed immediately and remained unchanged upon standing. When a solution of SCN −(aq) is added to the resulting precipitate, the precipitate dissolves and blood red solution of [Fe(SCN)(H2O)5]2+ complex is formed. The formation of the blood red complex is non-reversible. Explain the above observations and include relevant equations. [3] …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. ……………………………………………………………………………………..

5 © Jurong Pioneer Junior College 9729/03/J2 PRELIMINARY EXAM/2025 [Turn Over …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. For Examiner’s Use [Total: 17]

6 © Jurong Pioneer Junior College 9729/03/J2 PRELIMINARY EXAM/2025 2 Lucas Test, named after an American chemist, Howard Luca , is a simple qualitative test, using concentrated HCl in the presence of ZnCl2, to classify alcohols by observing the rate of turbidity, indicating the formation of insoluble alkyl halides. For Examiner’s Use (a) The rate of the Lucas Test is investigated, using tert-butanol, (CH3)3COH. When 1 dm3 of 0.0100 mol dm-3 of tert-butanol is reacted with 5.00 mol of HCl in the presence of ZnCl2, the concentration of tert-butyl chloride, (CH3)3CCl, formed over time is shown in the graph below. (i) Define the term order of reaction. [1] (ii) The same graph was obtained when the test was repeated with 7.5 mol of HCl in 1 dm3 of 0.0100 mol dm-3 of tert-butanol Using the information provided and the graph, deduce the