2025 Christ Church Prelim P2 QP

CHR 2025/Chemistry 6092/02/O/CZY [Turn Over CHRIST CHURCH SECONDARY SCHOOL 2025 PRELIMINARY EXAMINATION SECONDARY FOUR EXPRESS CANDIDATE NAME CLASS / CENTRE NUMBER S INDEX NUMBER CHEMISTRY 6092/02 Paper 2 19 August 2025 1 hour 45 minutes Candidates answer on the Question Paper No additional materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, index number, name and class on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs, or rough working. 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 questions. 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 21. The use of an approved scientific calculator is expected, where appropriate. ______________________________________________________________________ This document consists of 19 printed pages and 2 blank pages. For Examiner’s Use Section A Section B 10 11 Total 80

2 BLANK PAGE

3 Section A Answer all questions in the spaces provided. 1 A list of substances is provided below. methane copper(II) chloride sulfur dioxide sodium oxide lead(II) nitrate zinc sulfate (a) For the questions below, each substance can be used once, more than once or not at all. (i) Which substance exists as a simple molecule but can conduct electricity in aqueous state? .……………………………………………………………………………………… [1] (ii) Which substance, when dissolved in water, gives a blue precipitate with aqueous sodium hydroxide? .……………………………………………………………………………………… [1] (iii) Which substance contains an element with an oxidation state of +6? .……………………………………………………………………………………… [1] (iv) Which substance changes the colour of potassium manganate(VII) from purple to colourless? .……………………………………………………………………………………… [1] (b) Sodium oxide is a white solid that melts at 1132 oC. It dissolves in water to form an alkaline solution with effervescence. (i) Describe the arrangement and movement of the sodium oxide particles at 1140 oC. .……………………………………………………………………………………… .……………………………………………………………………………………… .……………………………………………………………………………………… [2] (ii) Write the chemical equation for the formation of this alkaline solution. .……………………………………………………………………………………… [1] (iii) State the observation you would expect when an aqueous solution of copper(II) chloride is added to the alkaline solution. .……………………………………………………………………………………… [1] [Total: 8]

4 2 Aqueous thiosulfate, S2O32−(aq), reacts with aqueous iodine according to the equation. I2(aq) + 2S2O32−(aq) → 2I−(aq) + S4O62−(aq) In a titration, 50.0 cm 3 of 0.1 mol/dm 3 aqueous thiosulfate was added to 40 cm 3 of 0.1 mol/dm3 aqueous iodine. (a) Determine the limiting reagent. Show your workings clearly. [2] (b) Calculate the percentage yield of iodide ions if only 0.0013 mol of iodide ions were produced at the end of the experiment. [2] (c) Explain, in terms of oxidation states, why the aqueous thiosulfate acts as a reducing agent in this reaction.. .……………………………………………………………………………………………… .……………………………………………………………………………………………… .……………………………………………………………………………………………… [2] (d) Explain whether this reaction can be considered a disproportionation reaction. .……………………………………………………………………………………………… .……………………………………………………………………………………………… [1] [Total: 7]

5 3 Fig. 3.1 shows the apparatus set-up of an experiment that a student performed. Fig. 3.1 Syringe 1 contains 90 cm3 of air. The air is forced over heated magnesium into syringe 2. The air is then forced back over the heated magnesium into syringe 1. The process is repeated several times until the volume of gas forced back into syringe 1 is constant. The apparatus is allowed to cool to room temperature. Fig. 3.2 shows the volume of gas in syringe 1 at the end of the experiment. Fig. 3.2 (a) Construct a chemical equation, including state symbols, for the above reaction. .……………………………………………………………………………………………… [1] (b) Name the major component of the gas remaining in syringe 1. .……………………………………………………………………………………………… [1] (c) Excess magnesium was used for the above reaction. Calculate the mass of magnesium that has reacted by the end of the experiment. [3] [Total: 5] heat syringe 1 syringe 2 magnesium syringe 1

6 4 The order of reactivity of five metals, copper, P, Q, R and S are investigated using a simple cell set-up shown in Fig. 4.1. Fig. 4.1 The voltmeter reading is recorded when each metal is being used as the metal strip. The results are summarised in Table 4.1. Table 4.1 Experiment metal strip direction of electron flow voltage / V 1 P from P to copper 0.52 2 Q from copper to Q 0.33 3 R from R to copper 1.51 4 S from S to copper 1.25 (a) Arrange the five metals in order of decreasing reactivity. .……………………………………………………………………………………………… [1] (b) If R forms ions of R+, construct the half equations that took place at the anode and cathode in Experiment 3. Anode: …………………………………………………………………………………… Cathode: …………………………………………………………………………………… [2] (c) Describe two differences between a simple cell and an electrolytic cell. .……………………………………………………………………………………………… .……………………………………………………………………………………………… .……………………………………………………………………………………………… .……………………………………………………………………………………………… [2] [Total:5] voltmeter metal strip copper strip filter paper soaked in potassium chloride solution wire wire

7 5 Ammonia is industrially manufactured in the Haber process. (a) Explain, with the help of an equation, why nitrogen and hydrogen are mixed in a ratio of 1 : 3 by volume. .……………………………………………………………………………………………… .……………………………………………………………………………………………… .……………………………………………………………………………………………… [2] (b) State the ideal conditions that are deployed in the Haber process. .……………………………………………………………………………………………… [1] (c) Name a method used to collect ammonia gas in the laboratory and provide a reason for using that method. .……………………………………………………………………………………………… .……………………………………………………………………………………………… [2] (d) Ammonia is used to manufacture nitric acid by first converting ammonia to nitrogen monoxide. 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(l) (i) In terms of the collision between reacting particles, state and explain how the rate changes when the pressure is increased. .……………………………………………………………………………………… .……………………………………………………………………………………… .……………………………………………………………………………………… .……………………………………………………………………………………… [2] (ii) Calculate the volume of gas that can be collected from 440 dm3 of ammonia at the end of the reaction if the yield is 40%. [2] [Total: 9]

8 6 The chemical composition of glass is known to be silicon (IV) dioxide as shown in Fig 6.1 which is the