2024 Prelims RI H2 Chem P2 (QP)

© Raffles Institution 2024 9729/02/S/24 [Turn Over RAFFLES INSTITUTION 2024 YEAR 6 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 9729/02 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 at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, 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. Do not write anything in it. You are reminded of the need for good English and clear presentation in your answers. 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 Examiner’s Use 1 / 15 2 / 19 3 / 22 4 / 19 Total / 75 This document consists of 24 printed pages.

© Raffles Institution 2024 9729/02/S/24 [Turn Over 2 Answer all questions in the space provided. 1 Boron and its compounds have diverse applications across industries. (a) (i) Write an equation to represent the fourth ionisation energy of boron. ……………………………………………………………………………………..…......... [1] (ii) Explain why the fourth ionisation energy of boron is much higher than that of carbon. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..…......... [2] (b) Borane, BH3, is a useful compound of boron. Borane undergoes complete combustion in excess oxygen to form boron trioxide, B2O3, as shown in equation 1. equation 1 BH3(g) + 3 2 (g) 1 2 (g) + 3 2 (g) (i) Draw a dot-and-cross diagram of the BH3 molecule. [1] (ii) State the shape and bond angle in BH3. ……………………………………………………………………………………..…......... [2] ∆Hr

© Raffles Institution 2024 9729/02/S/24 [Turn Over 3 (iii) Table 1.1 shows some bond energy data. Table 1.1 bond bond energy / kJ mol–1 B–B 293 B–H 330 B–O 536 B=O 837 Use the data in Table 1.1, together with data from the Data Booklet, to calculate the enthalpy change, ∆Hr, for the reaction in equation 1. [2] (i