2024 H1 Chem Prelim P2 QP VJC

© VJC 2024 8873/02/PRELIM/24 [Turn over CANDIDATE NAME CT GROUP VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 1 ……………………………………………….………….. …………………………….. CHEMISTRY 8873/02 Paper 2 Structured Questions Candidates answer on the Question Paper. 12 September 2024 2 hours Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your Name and CT group 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. Section A Answer all the questions. Section B 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 / 16 2 / 25 3 / 19 Section B 4 / 5 / 20 Total / 80 This document consists of 23 printed pages and 1 blank page.

2 © VJC 2024 8873/02/PRELIM/24 Section A Answer all questions in this section in the spaces provided. 1 (a) (i) Write down the electronic configurations of the following species. Na ………………………………………………………………………… Al2+ ………………………………………………………………………... [1] (ii) The electronic configuration of copper atom is 1s22s22p63s23p63d104s1. Sketch the shape of the filled orbital of copper atom with the highest energy on the axes in Fig. 1.1 and label the orbital. Fig. 1.1 [1] (iii) Write a balanced equation for the third ionisation energy of aluminium. …………………………………………………………………………………………....... [1] (iv) Explain why the third ionisation energy of aluminium is greater than the first ionisation energy of sodium. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………..…. [2] z y x

3 © VJC 2024 8873/02/PRELIM/24 [Turn over (b) Period 3 elements and their compounds show trends in their physical and chemical properties. (i) Sketch a graph to show the melting points of the first five elements in Period 3 on Fig. 1.2. Fig. 1.2 [2] (ii) Explain the variation in melting point of the first five Period 3 elements in terms of their structure and bonding. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… …………………………………………………………………………………………….. [3] melting point Na Mg Al Si P

4 © VJC 2024 8873/02/PRELIM/24 (iii) An excess of cold water is added to the oxide of sodium and the chloride of silicon separately. Describe the reactions of these compounds with water. Write relevant equation for any reaction that occurs and suggest the pH of the mixture produced in each case. …………………………………………………………………………………………………. …………………………………………………………………………………………….….... …………………………………………………………………………………………………. …………………………………………………………………………………………..…..…. …………………………………………………………………………………………………. ………………………………………………………………………………………….…..….. ……………………………………………………………………………………….….……... ………………………………………………………………………………………….…….... …………………………………………………………………………………………….……. ………………………………………………………………………………………….….…... ………………………………………………………………………………………..…...... [4] (c) Tennessine, Ts, is an unstable man -made element. It is found below astatine, At, in Group 17. The chemical properties of Ts and its compounds can be predicted. Suggest an equation for the reaction of NaTs and Br 2, assuming Ts follows the same trends as the other elements in Group 17. Explain your answer. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………..…... ………………………………………………………………………………………………….. ……………………………………………………………………………………………… [2] [Total: 16]

5 © VJC 2024 8873/02/PRELIM/24 [Turn over 2 (a) The reaction of ammonia with oxygen to form nitrogen monoxide, NO, is an important industrial process to manufacture nitric acid. The equation for this reaction is shown in equilibrium 2.1. 4NH3(g) + 5O2(g) ⇌ 4NO(g) + 6H2O(g) ΔH = –905 kJ mol−1 equilibrium 2.1 (i) The forward reaction in equilibrium 2.1 converts NH3 into NO. Draw the energy profile for this reaction in the diagram below. Label the following parts in your diagram. • reactants • products • activation energy, Ea • enthalpy change, ΔH [2] (ii) Write an expression for the equilibrium constant, Kc in equilibrium 2.1. ………………………………………………………………………………………….….. [1] (iii) Deduce the units of Kc in equilibrium 2.1. ……………………………………………………………………………………………... [1] energy progress of reaction

6 © VJC 2024 8873/02/PRELIM/24 (iv) The reaction in equilibrium 2.1 is carried out in a laboratory. 34.0 g of ammonia and 32.0 g of oxygen was allowed to react in a reaction chamber with volume of 50 cm3. At equilibrium, it was found that 20% of ammonia has reacted. Calculate a value for the equilibrium constant, Kc. [2] (v) Explain how a low temperature and a low pressure would lead to a high yield of nitrogen monoxide in equilibrium 2.1. …………………………………………………………………………………………….….... …………………………………………………………………………………….………..….. ……………………………………………………………………………..…………….…….. …………………………………………………………………………..……………….…….. …………………………………………………………………..……………………….…….. ………………………………………………………………………......………………..… [2] (vi) In industry, equilibrium 2.1 is carried out at a high temperature of 900°C. Suggest why the industry employs this temperature for equilibrium 2.1 instead of the conditions in (a)(v). ……………………………………………………………………………………….……….... ……………………………………………………………………………………………...….. …………………………………………………………………………………………………. ……………………………………………………………………………..…………....... [1]

7 © VJC 2024 8873/02/PRELIM/24 [Turn over (vii) Suggest which gas, oxygen or nitrogen monoxide, requires a higher pressure to be liquefied at the same temperature. Explain your answer in terms of intermolecular forces of attraction. ………………………………………………………………………………………….…….... …………………………………………………………………………………...………….…. ………………………………………………………………………………………….………. ……………………………………………………………………………………….....….….. ……………………………………………………………………………………..……….….. ………………………………