2024 Prelims YIJC H2 Chem P2 (QP)

©YIJC [Turn over YISHUN INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CG INDEX NO CHEMISTRY Paper 2 Structured Questions Candidates answer on the Question Paper. Additional Materials: Data Booklet 9729/02 10 September 2024 2 hours READ THESE INSTRUCTIONS FIRST This document consists of 18 printed pages and 6 blank pages. For Examiner’s Use 1 / 9 2 / 9 3 / 16 4 / 21 5 / 20 Penalty units significant figures Overall / 75 Write your name and class in the spaces at the top of this page. 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. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. The number of marks is given in brackets [ ] at the end of each question or part question.

©YIJC [Turn over 2 Answer all the questions in the spaces provided. 1 (a) Calcium carbide, CaC2 is a solid used in the production of ethyne, C2H2. Calcium carbide is produced when calcium oxide reacts with carbon forming calcium carbide and carbon monoxide. (i) Write the electronic configuration of calcium in calcium carbide. [1] (ii) Write an equation, with state symbols for the formation of calcium carbide. [2] (iii) Predict all possible intermolecular forces which could exist between carbon monoxide molecules. Explain how these forces arise. [3]

©YIJC [Turn over 3 (b) The German chemist Friedrich Wohler discovered that calcium carbide, CaC2 reacted with water releasing ethyne gas, C2H2 and calcium hydroxide. The ethyne gas was burnt in miner’s lamps and headlights of early motor vehicles for the purpose of illumination. The equation for the formation of ethyne from calcium carbide is as shown. CaC2(s) + H2O(l) → Ca(OH)2(aq) + C2H2(g) An impure sample of calcium carbide of mass 0.752 g was added to 50 cm3 of water. After all the calcium carbide had reacted, 20.00 cm3 of the reaction mixture was removed and titrated against 0.250 mol dmꟷ3 of hydrochloric acid and 34.60 cm3 of hydrochloric acid was required to neutralise the sample. It can be assumed that none of the impurities reacted. Calculate the percentage purity of calcium carbide. [3] [Total: 9]

©YIJC [Turn over 4 2 (a) Sodium halides are ionic compounds which have the same crystal structures. Table 2.1 shows data concerning solubility of