VJC 2021 Prelim H2P3 Qns [Final]

1 Ó VJC 2021 9729/03/PRELIM/21 [Turn over CANDIDATE NAME CT GROUP VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATIONS Higher 2 ……………………………………………….………….. …………………………….. CHEMISTRY 9729//03 Paper 3 Free Response Candidates answer on the Question Paper. 20 September 2021 2 hours Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your index number, name and CT group in the spaces at the top of this page. Write in dark blue or black pen. You may use a 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. If additional space is required, you should use the pages at the end of this booklet. The question number must be clearly shown. Section A Answer all questions. Section B Answer one question. A Data Booklet is provided. The use of an 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 Examiner’s Use 1 /21 2 /17 3 /22 4 or 5 /20 Total /80 This document consists of 34 printed pages and 2 blank pages.

2 Ó VJC 2021 9729/03/PRELIM/21 [Turn over Section A Answer all the questions in this section. 1 (a) Elements in the same group tend to form products with similar physical properties. However, the oxides of carbon and silicon have very different physical structures. While CO2 exists as a gas at room temperature, SiO2 is a solid. (i) Explain, in terms of structure and bonding, the difference in the physical states of CO2 and SiO2. [2] (ii) Describe the bonding in a single CO2 molecule. Include a fully labelled diagram showing how the different types of bonds are formed in terms of orbital overlap. [2] (iii) By considering the extent of overlap of the orbitals, suggest a reason why SiO2 does not form bonds similar to that of CO2. [1] ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ……………………………………………………………………………………………….

3 Ó VJC 2021 9729/03/PRELIM/21 [Turn over ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ……………………………………………………………………………………………….

4 Ó VJC 2021 9729/03/PRELIM/21 [Turn over (b) The extraction of iron from its ores typically involves the use of a Blast Furnace. One of the most common impurities in iron ore is silicon dioxide. To remove silicon dioxide, limestone is added. The calcium carbonate in limestone decomposes due to the high temperatures in the Blast Furnace to form calcium oxide. The calcium oxide then reacts with silicon dioxide to form calcium silicate, Ca2SiO4, which runs to the bottom of the Blast Furnace to be removed easily. (i) State the type of reaction between silicon dioxide and calcium oxide. [1] (ii) Define the term lattice energy. [1] (iii) Using the information given in Table 1.1 and relevant data from the Data Booklet, draw an energy level diagram and calculate a value for the lattice energy of calcium silicate, Ca2SiO4(s). Table 1.1 enthalpy change value / kJ mol–1 standard enthalpy change of atomisation of Ca(s) +178 standard enthalpy change of atomisation of Si(s) +456 O(g) + 2e– ® O2–(g) +650 Si4+(g) + 4O2–(g) ® SiO44–(g) –9304 standard enthalpy change of formation of Ca2SiO4(s) –994 [4] (iv) The reaction between calcium oxide and silicon dioxide also forms another form of calcium silicate, CaSiO3. Deduce whether the magnitude of the lattice energy of CaSiO3 is expected to be larger or smaller than that of Ca2SiO4. Explain your answer. [2] ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ……………………………………………………………………………………………….

5 Ó VJC 2021 9729/03/PRELIM/21 [Turn over ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ………………………………………………………………………………………………. ……………………………………………………………………………………………….

6 Ó VJC 2021 9729/03/PRELIM/21 [Turn over (c) Compound A, C9H9NO2, is insoluble in both aqueous acids and alkalis and does not react with sodium metal. When heated with aqueous hydrochloric acid, followed by careful addition of aqueous sodium hydroxide, compound B, C8H11NO is formed. Gentle warming of A with acidified KMnO4 gives the salt of compound C, C8H9NO. Further strong heating of the mixture forms the salt of compound D, C7H7NO2. Each mole of compounds B, C and D decolourises two moles of aqueous bromine. Compound C gives a pale yellow precipitate on warming with alkaline aqueous iodine. Sugg