2024 PU2 H1 Chem Paper 2 (QP)_MI

Class Adm No Candidate Name: This question paper consists of 19 printed pages and 1 blank page. 2024 Preliminary Exams Pre-University 2 H1 CHEMISTRY 8873/02 Paper 2 Structured Questions 9 Sep 2024 2 hours Candidates answer on the Question paper. Additional materials: Data Booklet READ THESE INSTRUCTIONS FIRST Do not turn over this question paper until you are told to do so Write your name, class and admission number 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, 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. 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. Question Section A Section B Total 1 2 3 4 5 6 7 Marks 11 18 16 6 9 20 20 80 H

2 Section A Answer all the questions in this section in the spaces provided. 1 Silicon compounds are used in the production of glass, ceramics, and refractory materials. Silicon dioxide is a major component of glass and is used in a wide range of applications, including construction, optics, and consumer products. (a) A sample of silicon contains three isotopes, as shown in Table 1.1. Table 1.1 Isotope Percentage abundance / % 28Si 92.23 29Si 4.67 30Si 3.1 (i) Define the term relative atomic mass of silicon. ………………………………………………………………………………………………… [1] (ii) Calculate the relative atomic mass of silicon from this sample, giving your answer in two decimal places. [1] (b) (i) State the full electronic configuration of silicon. Si : .…………………………………………………………………………………………… [1] (ii) With reference to the Data Booklet, compare the values of second and third ionisation energies of silicon. Explain why these two energies are different and include an equation representing the third ionisation energy of silicon in your answer. …………………………………………………………………………………………………… …………………………………………………………………………………………………… ………………………………………………………………………………………………… [3]

3 [Turn over (c) Describe the reaction, if any, of silicon dioxide with water. Include the approximate pH value of any resulting solution. ……………………………………………………………………………………………………… [1] (d) Silicon dioxide can react with carbon under high temperature to form silicon carbide, SiC. Silicon carbide has a high melting point of 2730 °C. It is very hard and can be used as a semiconductor material. (i) Suggest the type of structure and bonding of SiC. Structure : ………………………………………………………………………………………. B