2024 RI H1Chem Prelims P2 Questions

RAFFLES INSTITUTION 2024 YEAR 6 PRELIMINARY EXAMINATION Higher 1 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 8873/02 Paper 2 Structured Questions 10 September 2024 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Do not open this question booklet until you are told to do so. Write your name, class and index number in the spaces provided at the top of this page. Write in dark blue or black pen. You may use a n 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. A Data Booklet is provided. Do not write anything in it. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 23 printed pages and 1 blank page. For Examiner’s Use Section A 1 / 11 2 / 8 3 / 11 4 / 10 5 / 11 6 / 9 Section B (Please circle the question you have attempted) 7 / 20 8 / 20 Total / 80

2 © Raffles Institution 2024 8873/02/S/24 [Turn Over Section A Answer all the questions in this section in the spaces provided. 1 (a) Complete Table 1.1 for each species. Table 1.1 species number of protons number of neutrons number of electrons electronic configuration K19 40 1s2…………………………………... 24 28 21 1s2…………………………………... [3] (b) The strength of interaction between particles determines whether the substance is a solid, liquid or gas at room temperature. Magnesium oxide, MgO, is a solid while sulfur trioxide, SO 3, is a liquid at room temperature. (i) Explain in terms of structure and bonding, why MgO is a solid while SO3 is a liquid at room temperature. ……………………………………………………………………………………..………. ……………………………………………………………………………………..………. ……………………………………………………………………………………..…….… ……………………………………………………………………………………...……… ……………………………………………………………………………………..……[2] (ii) Suggest one other difference in the physical properties of MgO and SO3. ……………………………………………………………………………………..………. …………………………………………………………………………………..………[1]

3 © Raffles Institution 2024 8873/02/S/24 [Turn Over (iii) Draw a ‘dot -and-cross’ diagram to show the arrangement of outer electrons in MgO. [2] (c) 3-phenylpropenal is the compound which gives cinnamon its characteristic flavour and odour. 3-phenylpropenal (i) Draw the two cis-trans isomers of 3 -phenylpropenal and label each structure. Explain how this isomerism arises. ……………………………………………………………………………………..………. ……………………………………………………………………………………..………. ……………………………………………………………………………………..………. ……………………………………………………………………………………..………. …………………………………………………………………………………..………[3] [Total: 11]

4 © Raffles Institution 2024 8873/02/S/24 [Turn Over 2 (a) An ideal gas consists of particles of negligible volume and the gas particles exert negligible attractive forces on one another. Most gases are non-ideal but under certain conditions, some gases behave like ideal gases. One gas that behaves like this is oxygen. The volume of oxygen occupied by a fixed amount of oxygen at different temperatures is shown in Fig. 2.1. Fig. 2.1 (i) Describe the relationship between the volume of oxygen and temperature. ……………………………………………………………………………………..…........ …………………………………………………………………………………………..[1] (ii) State the conditions which would result in the greatest intermolecular forces between gaseous oxygen molecules. …………………………………………………………………………………………..[1] T/K 0 V constant p

5 © Raffles Institution 2024 8873/02/S/24 [Turn Over (iii) Liquefaction of gases is the process by which substances in their gaseous state are converted to the liquid state. It is difficult to liquefy oxygen but easy to liquefy ammonia, NH 3. With the aid of a labelled diagram, explain why it is easier to liquefy ammonia. Your diagram should include two ammonia molecules. ……………………………………………………………………………………..…........ …………………………………………………………………………………………..[3] (b) Draw a diagram to illustrate the structure of graphene and explain why graphene • is a good electrical conductor. • has high tensile strength. ……………………………………………………………………………………..…………… ……………………………………………………………………………………..…………… ……………………………………………………………………………………..…………… ……………………………………………………………………………………..…………… ……………………………………………………………………………………..…………… ……………………………………………………………………………………..…………… ……………………………………………………………………………………..…………… ………………………………………………………………………………..……………….. [3] [Total: 8]

6 © Raffles Institution 2024 8873/02/S/24 [Turn Over 3 At high temperatures, steam and methane react to produce hydrogen gas. 2H2O(g) + CH4(g) ⇌ CO2(g) + 4H2(g) ∆H = +168 kJ (a) Given that the percentage yield of hydrogen increases with increasing temperature, deduce whether the forward reaction is exothermic or endothermic. Explain your answer using references to the equilibrium position. ……………………………………………………………………………………..……………... …………………………………………………………………………………..………………... …………………………………………………………………………………..……………..[1] (b) State and explain how the percentage yield of hydrogen might alter when the pressure is decreased. ……………………………………………………………………………………..……………... …………………………………………………………………………………..………………... ……………………………………………………………………………………..……………... …………………………………………………………………………………..………………... ……………………………………………………………………………………..……………... …………………………………………………………………………………..……………..[2] (c) State and explain the effect that each of the following has on the value of the equilibrium constant for the above equilibrium. increase in temperature ………………………………………………………………………………..…………..…........ …………………………………………………………………………………………..……..[1] introduction of a catalyst …………………………………………..………………………………………………..…........ ……………………………………………………………………………..…………………..[1]

7 © Raffles Institution 2024 8873/02/S/24 [Turn Over (d) When the temperature of the reaction mixture is increased, the reaction rate increases. Explain this in terms of the Boltzmann distribution. ……………………………………………………………………………………..……...……… ……………………………………………………………………………………………………. ………………………………………………………………………………...……..…………… …………………………………………………………………………………....………………. ………………………………………………………………………………...……..…………… …………………………………………………………………………….……..…………….[2] (e) The reaction of steam with methane occurs in two stages. Stage 1 H2O(g) + CH4(g) ⇌ CO(g) + 3H2(g) ∆H = +210 kJ mol–1 Stage 2 H2O(g) + CO(g) ⇌ CO2(g) + H2(g) ∆H = −42 kJ mol–1 Complete and label the reaction pathway diagram for the overall reaction between steam and methane showing both of these stages. [4] [Total: 11] energy reaction progress

8 © Raffles Institution 2024 8873/02/S/24 [Turn Over 4 Fermented milk has a sour taste due