2024 CHIJ Sec 4E Chemistry Prelim P2

O CONVENT OF THE HOLY INFANT JESUS SECONDARY Preliminary Examination in preparation for the General Certificate of Education Ordinary Level 2024 CANDIDATE NAME CLASS REGISTER NUMBER CHEMISTRY Paper 2 Candidates answer on the Question Paper. No Additional Materials are required. 6092/02 22 August 2024 1 hour 45 minutes 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. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 24. The use of an approved scientific calculator is expected, where appropriate. This document consists of 22 printed pages and 2 blank pages. [Turn over

2 CHIJSec/2024/OLevelPrelim/6092/02 BLANK PAGE

3 CHIJSec/2024/OLevelPrelim/6092/02 [Turn over Section A Answer all questions. The total mark for this section is 70. 1 Some ionic equations, A to F, are shown. A H+ + OH– → H2O B Fe3+ + 3OH– → Fe(OH)3 C Cl2 + 2Br– → Br2 + 2Cl– D Na+ + e – → Na E 2Cl– → Cl2 + 2e – F NH4+ + OH– → H2O + NH3 Each letter may be used once, more than once or not at all. Give the letter, A to F, for the equation which represents (a) a displacement reaction. ………………….…….. [1] (b) a precipitation reaction. ………………….…….. [1] (c) a redox reaction. ………………….…….. [1] (d) a neutralisation reaction. ………………….…….. [1] (e) Give the letters of the two equations that, when combined, represent a decomposition reaction. ………………….……. and ………………….……. [1] [Total: 5]

4 CHIJSec/2024/OLevelPrelim/6092/02 2 Steel is an alloy of iron which contains carbon. There are many different types of steel that can be used for different purposes. Fig. 2.1 shows the arrangement of atoms in pure iron. Fig. 2.1 (a) In the diagram below, draw the arrangement of atoms in steel. You should complete the legend provided. [2] (b) Use your diagram and Fig. 2.1 to explain why (i) steel is a mixture of elements. …………..………………………………………………………………...……………......... …………..………………………………………………………………...…………….... [1] (ii) steel is harder than pure iron. …………..………………………………………………………………...……………......... …………..………………………………………………………………...……………......... …………..………………………………………………………………...…………….... [2] (c) Describe how the particles in steel allow it to conduct electricity. …………………………………………………….……….……………………………………….. ……………………………………………………………...………………………………..….. [1] Legend: iron carbon

5 CHIJSec/2024/OLevelPrelim/6092/02 [Turn over (d) Stainless steel is a type of steel that also contains chromium. Chromium can displace iron from its salt solution. Explain how the addition of chromium prevents stainless steel from rusting. ………………………………………………………….……….………………………………….. ………………………………………………………….……….………………………………….. ……………………………………………………………...………………………………..…. [2] [Total: 8]

6 CHIJSec/2024/OLevelPrelim/6092/02 3 The equation for the reaction between tetrachloromethane gas and steam is shown below. CCl4(g) + 2H2O(g) → CO2(g) + 4HCl(g) ∆H = –130kJ Table 3.1 shows some bond energies. Table 3.1 (a) Using the information provided, calculate (i) the energy absorbed to break the bonds in the reactants. energy absorbed ……………………. kJ [1] (ii) the bond energy for the H–Cl bond, in kJ/mol. bond energy ……………………. kJ/mol [1] (b) Explain, in terms of bond-breaking and bond-making, why the overall enthalpy change of this reaction is negative. ………………………………………………………….……….………………………………….. …………………………………………………….……….……………………………………….. …………………………………………………….……….……………………………………….. ……………………………………………………………...………………………………..…. [3] [Total: 5]

7 CHIJSec/2024/OLevelPrelim/6092/02 [Turn over 4 Table 4.1 shows some information about three different types of salts and the temperature change when they dissolve in water. Table 4.1 name of salt name of acid used to make the salt name of other compound used to make the salt temperature change when salt dissolves in water (°C) calcium chloride hydrochloric acid calcium carbonate +5 ammonium chloride –20 calcium sulfate calcium nitrate N.A. (a) Fill in the blanks in the table above. [2] (b) Explain why calcium carbonate cannot be reacted with the acid you suggested in (a) to produce calcium sulfate. ………………………………………………………………..…………………………………….. ……………………………………………………………...………………………………..…. [1] (c) Complete the energy profile diagrams to show the products and enthalpy changes when calcium chloride, CaCl2, and ammonium chloride, NH4Cl, are dissolved in water. [3] [Total: 6] progress of reaction energy CaCl2(s) progress of reaction energy NH4Cl(s)

8 CHIJSec/2024/OLevelPrelim/6092/02 5 Fig. 5.1 gives the experimental setup of two cells. Both electrodes P and Q are made of graphite. Cell 1 Cell 2 Fig. 5.1 (a) (i) Write the half-equations for the reactions occurring at the zinc and copper electrodes in Cell 1. zinc electrode: ………………………………………………………………………... copper electrode: ……………………………………………………………………. [2] (ii) Hence, describe the expected observations in Cell 1. …………..………………………………………………………………...……………......... …………..………………………………………………………………...……………......... …………..………………………………………………………………...……………......... …………..………………………………………………………………...…………….... [2] (b) The voltage of Cell 1 was found to be 1.10 V. Suggest the voltage if the copper electrode in Cell 1 was replaced with silver. Explain your reasoning. ………………………………………………………….……….………………………………….. …………………………………………………….……….……………………………………….. ………………………………………………………………..…………………………………….. ……………………………………………………………...………………………………..…. [2] dilute hydrochloric acid aqueous copper(II) sulfate copper zinc electrode P electrode Q

9 CHIJSec/2024/OLevelPrelim/6092/02 [Turn over (c) After a few minutes, 16 cm3 of gas was collected electrode P in Cell 2. Electrode P is the negative electrode while electrode Q is the positive electrode. What volume of gas would you expect at electrode Q? Include half-equations to support your answer. ………………………………………………………….……….………………………………….. …………………………………………………….……….……………………………………….. ………………………………………………………………..…………………………………….. …………………………………………………….……….……………………………………….. ………………………………………………………………..…………………………………….. ……………………………………………………………...………………………………..…. [3] [Total: 9]

10 CHIJSec/2024/OLevelPrelim/6092/02 6 A student investigates the reaction of excess magnesium carbonate with 0.10 mol/dm3 of hydrochloric acid at 25°C (experiment 1). MgCO3 + 2HCl → MgCl2 + H2O + CO2 Fig. 6.1 shows the volume of carbon dioxide gas released as the reaction proceeds for experiment 1. Fig. 6.1 (a) From Fig. 6.1, determine the volume of carbon dioxide gas obtained from this reaction. volume of carbon dioxide ……………………. cm3 [1] (b) Hence, calculate the volume of 0.10 mol/dm3 of hydrochloric acid used in the experiment. (1 mole of any gas occupies 24 dm3 at room temperature and pressure) volume of hydrochloric acid ……………………. cm3 [2] time / min