2025 H1 Chem JC2 Prelim P2 (for sharing)_JPJC

© Jurong Pioneer Junior College [Turn over Name:____________________________________ Class:_____________ JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2025 CHEMISTRY 8873/02 Higher 1 29 August 2025 Paper 2 2 hours Additional materials: 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 (60 marks) Answer all the questions. Section B (20 marks) Answer one question. 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 Section A 1 15 2 16 3 11 4 12 5 6 Section B 6 20 7 20 Penalty (delete accordingly) Missing/wrong units in final answer –1 / NA Total 80 This document consists of 24 printed pages and 4 blank pages.

2 © Jurong Pioneer Junior College 8873/02/J2 PRELIMINARY EXAMINATION /2024 Section A Answer all the questions in this section, in the spaces provided. 1 A unknown metal sulfate has the formula MSO4. The hydrated form of the metal sulfate has the formula MSO4.xH2O. For Examiner’s Use (a) Name the types of bonds that are present in the metal sulfate. Electrostatic forces of attraction between oppositely charged ions (ionic bond) and covalent bonds. [2] (b) When 6.24 g of the hydrated metal sulfate is strongly heated, thermal decomposition occurs. In addition to water, a solid oxide , MO, and a gaseous oxide are also produced. The solid oxide had a mass of 1.99 g. The volume of the gaseous oxide produced was 600 cm 3 at r.t.p. A strongly acidic solution is produced when the gaseous oxide is dissolved in water. (i) Write a balanced equation for the thermal decomposition of the hydrated metal sulfate. MSO4.xH2O → MO + SO3 + xH2O [1] (ii) Calculate the relative atomic mass of metal M. Hence, suggest the identity of metal M. Amount of gaseous oxide = (600 x 10–3) / 24 = 0.0250 mol 1 gaseous oxide ≡ 1 MO Amount of MO = 0.0250 mol Ar of M = (1.99 / 0.025) – 16 = 63.6 M is Cu [3] (iii) Using your answer in (b)(ii), calculate the integer x in MSO4.xH2O. Mr of hydrated metal sulfate = 63.6 + 32.1 + 64.0 + 18x = 159.7 + 18x Amount of MO = Amount of MSO4.xH2O 0.0250 = 6.24 159.7+18x 3.993 + 0.45x = 6.24 0.45x = 2.25 x = 4.99 x ≈ 5 [2] (c) The metal ion, M2+, can catalyse the hydrolysis of ester N into butanedioic acid and methanol as shown below. OH OH O O