2024 ACJC Prelim H1 Chem Paper 2 OP

This document consists of 20 printed pages and 2 blank pages. s Anglo-Chinese Junior College JC2 Preliminary Examination Higher 1 CANDIDATE NAME FORM CLASS TUTORIAL CLASS 2CHX INDEX NUMBER CHEMISTRY Paper 2 Structured Questions Candidates answer on the Question Paper. Additional Materials: Data Booklet 8873/02 21 August 2024 2 hours READ THESE INSTRUCTIONS FIRST Write your name and index number in the spaces 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, highlighters, glue or correction fluid. Section A Answer all questions. Section B Answer one question. The use of 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 Examiners’ use only Section A 1 / 14 2 / 10 3 / 13 4 / 10 5 / 13 Section B 6 or 7 / 20 Presentation Total / 80

2 © ACJC2024 8873/Preliminary Examination/2024 [Turn over Section A Answer all the questions in this section in the spaces provided. 1 Aqueous hydrogen peroxide, H2O2, slowly forms water and oxygen at room temperature and pressure, r.t.p. This rate of reaction is increased by the addition of a small amount of solid manganese(IV) oxide. 2H2O2(aq) 2H2O(l) + O2(g) (a) (i) Define the term, rate of reaction. ……………………………………………………………………………………………. …………………………………………………………………………………………[1] (ii) State the role of manganese(IV) oxide and explain the reason. ………………………………………………………………………………………….… …………………………………………………………………………………………[2] (iii) State the test for oxygen gas. …………………………………………………………………………………………[1] (iv) State the effect on the mass of oxygen gas produced if the mass of manganese(IV) oxide is increased. …………………………………………………………………………………………[1]

3 © ACJC2024 8873/Preliminary Examination/2024 [Turn over (b) A student investigates the rate of formation of oxygen gas when manganese(IV) oxide is added to aqueous hydrogen peroxide. The volume of oxygen gas formed is measured at regular time intervals at r.t.p. The results are plotted onto the graph in Fig. 1.1. Fig. 1.1 (i) State how the graph in Fig. 1.1 shows the rate of reaction at time t2, is lower than at time t1. …………………………………………………………………………………………[1] (ii) Explain, using collision theory, why the rate of reaction at time t2 is lower than at time t1. ………………………………………………………………………………………….… …………………………………………………………………………………………[2] (iii) On Fig. 1.1, sketch the graph obtained when the experiment is repeated using aqueous hydrogen peroxide at a higher temperature. All other conditions remain the same. [1]

4 © ACJC2024 8873/Preliminary Examination/2024 [Turn over (c) The experiment is repeated at an increased temperature. All other conditions stay the same. Draw labelled Boltzmann distribution curve(s) to explain why the rate of reaction increases at a higher temperature. ………………………………………………………………………………………………….… ………………………………………………………………………………………………….… ………………………………………………………………………………………………….… …………………………………………………………………………………………………[3] (d) Manganese(IV) oxide is added to 20 cm3 of aqueous hydrogen peroxide. The total volume of oxygen gas produced is 72 cm3 at r.t.p. 2H2O2(aq) 2H2O(l) + O2(g) (i) Calculate the number of moles of hydrogen peroxide that reacted. [1] (ii) Calculate the concentration of aqueous hydrogen peroxide in g dm–3. [1] [Total: 14] kinetic energy fraction of particles

5 © ACJC2024 8873/Preliminary Examination/2024 [Turn over BLANK PAGE

6 © ACJC2024 8873/Preliminary Examination/2024 [Turn over 2 Methane reacts with steam to produce hydrogen gas. equation 2.1 CH4(g) + H2O(g) CO(g) + 3H2(g) ΔH = +200 kJ mol–1 The reaction takes place at 1000 °C and 100 kPa pressure. (a) The reaction is reversible and reaches dynamic equilibrium in a closed system. (i) State two features of a dynamic equilibrium. ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… …………………………………………………………………………………………[2] (ii) Sketch a labelled graph to show how the rates of the forward and reverse reactions change from the start of the reaction to the time the reaction reaches equilibrium. [2] (b) State and explain, the effect on the amount of hydrogen when: (i) the pressure is increased ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… …………………………………………………………………………………………[2] (ii) the temperature is increased ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… …………………………………………………………………………………………[2] time rate / mol–1 dm3 s–1

7 © ACJC2024 8873/Preliminary Examination/2024 [Turn over (c) (i) Write the expression for the equilibrium constant, Kc, for equation 2.1. [1] (ii) State the effect of decreasing temperature on the equilibrium constant, Kc. ……………………………………………………………………………………….…… …………………………………………………………………………………………[1] [Total: 10]

8 © ACJC2024 8873/Preliminary Examination/2024 [Turn over 3 Perspex, a transparent thermoplastic, is commonly utili sed in sheet form as a lightweight, shatter-resistant substitute for glass. It also finds application as a casting resin, inks, and coatings. Moreover, Perspex, poly(methyl 2-methylpropenoate), is formed by polymerising methyl 2- methylpropenoate, a single monomer. (a) (i) Identify all the functional groups in methyl 2-methylpropenoate …………………………………………………………………………………………[1] (ii) State the functional group that reacts with bromine in CC l4 and the expected observation. …………………………………………………………………………………………[1] (b) (i) Describe the term polymer. ……………………………………………………………………………………….…… …………………………………………………………………………………………[1] (ii) State the type of polymerisation the monomer undergoes to form Perspex. Draw the structural formula for Perspex, showing two monomer units. [2]

9 © ACJC2024 8873/Preliminary Examination/2024 [Turn over (iii) Describe two characteristics of thermoplastics in terms of their structure and bonding. ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… …………………………………………………………………………………………[2] (iv) State two different physical properties of thermoplastics and thermosets. ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… ……………………………………………………………………………………….…… …………………………………………………………………………………………[2] (v) Although Perspex is a thermoplastic, it has o