2023 VS 6092 P2 Chemistry Prelim

Class Register Number Name 6092/02 CHEMISTRY 23/4P/6092/2 PAPER 2 Tuesday 29 August 2023 1 hour 45 minutes VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA SCHOOL VICTORIA VICTORIA SCHOOL PRELIMINARY EXAMINATION SECONDARY FOUR READ THESE INSTRUCTIONS FIRST Write your name, class and index number on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions in the spaces provided. Section B Answer all three questions. The last question is in the form either/or. Answer all questions in the spaces provided. The number of marks is given in brackets [ ] at the end of each question or part question. The use of an approved scientific calculator is expected, where appropriate. A copy of the Periodic Table is printed on page 22. This question paper consists of 22 printed pages, including the cover page. [Turn Over Section A / 50 Section B / 30 Total / 80 Deductions Presentation Significant Figures Units 477

2 © Victoria School 23/4P/6092/2 Section A Answer all the questions in this section in the spaces provided. The total mark for this section is 50. A1 Select substances from the list to answer the following questions. You may use each substance once, more than once or not at all. CuO K CO2 Ca(OH)2 SO3 Ni Cl2 SO2 (a) Which substance is a product of respiration? ………………………………………………...………………………………………………..[1] (b) Which substance gives a lilac flame when added to water? ………………………………………………...………………………………………………..[1] (c) Which substance is a catalyst in the hydrogenation of alkenes? ………………………………………………...………………………………………………..[1] (d) Which substance can produce effervescence when reacted with ammonium chloride? ………………………………………………...………………………………………………..[1] (e) Which two substances when added together will form only one compound? ………………………………………………...………………………………………………..[1] (f) Which substance is emitted by volcanoes and lead to global warming and acid rain? ………………………………………………...………………………………………………..[1] [Total: 6] 478

3 © Victoria School 23/4P/6092/2 A2 Fig. 2.1 shows the structures of compound S and compound T. Fig. 2.1 (a) Compound S is a weak acid while compound T is a strong acid. (i) Explain why compounds S and T are classified as acids. ……………………………………………………………………………………...…...[1] (ii) A student states that compound s S and T can be identified by making measurements using magnesium strips. Describe how the student can show this. …………………………………………………………………………………...……....... …………………………………………………………………………………...……....... ……………………………………………………………………………...…………...[2] (iii) Describe what will be observed when compound S is added into a test -tube of aqueous iodine. ……………………………………………………………………………………...…...[1] compound S compound T 479

4 © Victoria School 23/4P/6092/2 (b) 25.0 cm3 of 1.2 mol/dm3 compound S was titrated with aqueous sodium hydroxide. The pH of the mixture was monitored with a pH probe connected to a datalogger. Fig. 2.2 shows the pH curve of the titration. Fig. 2.2 (i) Write the ionic equation when compound S reacts with dilute sodium hydroxide. [1] (ii) State the pH of the salt formed. ……………………………………………………………………………………...…...[1] (iii) 25.0 cm3 of 1.2 mol/dm3 compound T is titrated with the same aqueous sodium hydroxide. Sketch the pH curve on Fig. 2.2. [2] (c) 50 cm3 of 1.2 mol/dm3 compound S and compound T were placed in separate beakers. 1.0 g of calcium carbonate was added into each beaker. (i) A student predicted the reaction with compound T will complete earlier. Explain why the student is wrong. …………………………………………………………………………………...……....... ……………………………………………………………………………...…………...[1] volume of aqueous sodium hydroxide / cm3 pH 480

5 © Victoria School 23/4P/6092/2 (ii) Calculate the volume of gas produced when calcium carbonate reacts with compound S. [3] (d) Compound S and methanol was warmed with some concentrated compound T. Draw the displayed formula of the compound formed. [2] [Total: 14] 481

6 © Victoria School 23/4P/6092/2 A3 (a) Monosodium glutamate, commonly known as MSG, can be prepared by reacting aqueous glutamic acid with aqueous sodium hydroxide. + NaOH → + H2O monosodium glutamate In a titration, 25.0 cm 3 aqueous glutamic acid reacts with 22.4 0 cm3 of 1.0 mol/dm 3 sodium hydroxide. + 2NaOH → + 2H2O disodium glutamate (i) Explain why titration must be used to prepare monosodium glutamate from aqueous glutamic acid. …………………………………………………………………………………...……....... ……………………………………………………………………………...…………...[1] (ii) State the volume of 1.0 mol/dm3 sodium hydroxide to be added into 250 dm 3 of the same aqueous glutamic acid to produce a pure solution of monosodium glutamate. Explain your answer. …………………………………………………………………………………...……....... …………………………………………………………………………………...……....... ……………………………………………………………………………...…………...[2] (b) Copper(II) glutamate is prepared by reacting aqueous glutamic acid with excess copper(II) carbonate. (i) Name another chemical which reacts with aqueous glutamic acid to form copper(II) glutamate. ……………………………………………………………………………...…………...[1] (ii) State the advantage of using excess copper( II) carbonate instead of aqueous glutamic acid in the preparation of copper(II) glutamate. …………………………………………………………………………………...……....... ……………………………………………………………………………...…………...[1] [Total: 5] 482

7 © Victoria School 23/4P/6092/2 A4 Ethanol is manufactured by the reaction between ethene and steam. C2H4(g) + H2O(g) → C2H5OH(g) Table 4.1 shows the bond energies of some chemical bonds. bond bond energy in kJ/mol bond bond energy in kJ/mol O = O 498 O − H 463 O − O 144 C − H 414 C − C 346 C = O 804 C = C 610 C − O 358 (a) Using the bond energies provided, calculate the total energy change for this reaction. [3] Table 4.1 483

8 © Victoria School 23/4P/6092/2 (b) Complete the energy profile diagram for the reaction between ethene and steam. Your diagram should show: • the products of the reaction • the energy profile and activation energy, Ea(1), for the reaction • the energy profile and activation energy, Ea(2), for the reaction when nickel is added • the enthalpy change of reaction, ΔH [4] [Total: 7] energy / kJ progress of reaction C2H4(g) + H2O(g) 484

9 © Victoria School 23/4P/6092/2 A5 Ideonella sakaiensis is a type of bacteria found in cow stomachs that can break down polyethylene terephthalate (PET), a type of plastic commonly used to produce bottles. The structure of PET is shown in Fig. 5.1. (a) PETase produced by th