2018 C1 Promotional Exam Paper 2

This document consists of 12 printed pages. HWA CHONG INSTITUTION C1 Promotional Examination Higher 2 NAME CT GROUP 18S CHEMISTRY Paper 2 Structured questions Candidates answer on the Question Paper. Additional Materials: Data Booklet. 9729/02 2 October 2018 1 hour 5 minutes READ THESE INSTRUCTIONS FIRST Write your name and CT group 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, highlighters, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. FOR EXAMINERS’ USE ONLY Paper 1 Paper 2 Paper 3 Multiple Choice Structured Free Response Q1 / 10 Q1 / 20 Q2 / 14 Q2 / 3 / 20 Q3 / 16 Deductions Deductions / 20 Subtotal: / 40 Subtotal: / 40

2 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 2 Answer all the questions. 1 Cyclohexane can be produced by reacting benzene with hydrogen under certain conditions. C6H6(g) + 3H2(g) = C6H12(g) Vessel A contains benzene gas at a pressure of x atm and vessel B contains hydrogen gas at a pressure of 5.67 atm. The flasks were kept at a temperature of 600 K. When the two flasks are connected and the gases mixed in the presence of a suitable catalyst with the temperature maintained at 600 K, they react to give gaseous cyclohexane. It was found that at equilibrium, the partial pressures of cyclohexane and benzene were 0.61 atm and 2.70 atm respectively. (a) (i) Write an expression for Kp for this equilibrium. [1] (ii) Find the partial pressure of hydrogen at equilibrium, given that Kp = 0.0305 atm−3. [1] (iii) The two vessels have a combined volume of 6.0 dm3. Show that the volume of vessel B is 4.0 dm3 and hence determine x. [3]

3 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 2 (b) Using relevant bond energy data from the Data Booklet, calculate the enthalpy change for the reaction of benzene gas and hydrogen gas to give cyclohexane gas. [2] (c) Deduce how the Kp will change if: I the catalyst was removed: ..………………………..………………………………………………………………………… ..………………………..………………………………………………………………………… ..………………………..………………………………………………………………………… II the temperature was increased: ..………………………..………………………………………………………………………… ..………………………..………………………………………………………………………… ..………………………..………………………………………………………………………… ..………………………..………………………………………………………………………… [3] [Total: 10]

4 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 2 2 Methylbenzene reacts with liquid bromine under different reaction conditions to p