2024 Prelims VJC H2 Chem P2 (QP)

1 © VJC 2024 9729/02/PRELIM/24 [Turn over CANDIDATE NAME CT GROUP VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 ……………………………………………….………….. …………………………….. CHEMISTRY 9729/02 Paper 2 Structured Questions Candidates answer on the Question Paper. 12 September 2024 2 hours Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and CT group 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. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 20 2 / 22 3 / 16 4 / 17 Total / 75 This document consists of 20 printed pages.

2 © VJC 2024 9729/02/PRELIM/24 1 (a) The Pauling electronegativity values, EN, for the elements in the first two periods of the Periodic Table range from 1.0 to 4.0. The elements X, Y and Z are all in the first two periods of the Periodic Table. Their EN values are shown in Table 1.1. Table 1.1 element EN X 1.0 Y 2.1 Z 4.0 Substances exist with formulae XZ, YZ and Z2. (i) Use Table 1.1 to deduce the group of the Periodic Table that X and Z belong to. X belongs to Group …………………………………. Z belongs to Group …………………………………. [1] (ii) Suggest the structure and bonding present in XZ. ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………..…………….... [1] (iii) Arrange XZ, YZ and Z2 in order of increasing melting point. ………………………………………………………………………………..…………….... [1] (b) (i) Write the full electronic configuration of an aluminium atom. ………………………………………………………………………………..…………….... [1] (ii) Write an equation to show the third ionisation energy of aluminium. ………………………………………………………………………………..…………….... [1] (iii) Explain why the third ionisation energy of aluminium is greater than the first ionisation energy of sodium. ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………..…………….... [2]

3 © VJC 2024 9729/02/PRELIM/24 [Turn over (c) Two Period 3 elements, U and V, burn separately in oxygen to form solid oxides. The oxide of U is insoluble in water. The oxide of V dissolves in water to form solution W. Solution W reacts with the oxide of U at room temperature and dissolves it. V has a larger atomic radius than U. (i) Identify U and V. U is …………………………………. V is …………………………………. [2] (ii) Write an equation for the reaction between oxide of U and solution W. ………………………………………………………………………………..…………….... [1] (d) (i) State the total numbers of protons, neutrons and electrons in the NO3 – ion. Total number of protons: …………………………………. Total number of neutrons: …………………………………. Total number of electrons: …………………………………. [1] (ii) Similar to carbonate salts, c opper(II) nitrate, Cu(NO3)2, and barium nitrate, Ba(NO 3)2, decompose when heated. Compare the decomposition temperatures of these two compounds. Explain your answer. ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………..…………….... [2] (iii) Sketch the shape of and label a filled orbital in Cu2+(aq) ion with the highest energy in Fig. 1.1. Fig. 1.1 [1] z y x

4 © VJC 2024 9729/02/PRELIM/24 (iv) Compound T, an anhydrous Group 2 bromide, is dissolved in water and titrated against aqueous silver nitrate. A solution containing 0.250 g of T requires 33.65 cm3 of 0.0500 mol dm –3 AgNO3(aq) for complete reaction. Identify T. Show your working. [2] (e) HCl is a product of several different reactions. Some of these are shown in Fig. 1.2. Fig. 1.2 (i) Describe the reaction of SiCl4 with water in reaction 1. Write an equation for the reaction and state the pH of the resultant mixture. ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………..…………….... [1]

5 © VJC 2024 9729/02/PRELIM/24 [Turn over In reaction 2, NaCl reacts with concentrated H2SO4 to form HCl and NaHSO4 only. Similarly, NaBr reacts with concentrated H 2SO4 to form HBr and NaHSO 4. HBr reacts further with concentrated H2SO4 to form Br2 and SO2. (ii) State the types of reaction that occur when NaBr reacts with concentrated H2SO4 and when HBr reacts with concentrated H2SO4. reactants type of reaction NaBr and concentrated H2SO4 HBr and concentrated H2SO4 [1] (iii) Write an equation for the reaction of HBr with concentrated H2SO4. ………………………………………………………………………………..…………….... [1] (iv) Suggest an explanation for the difference in the reactions when HCl and HBr react with concentrated H2SO4. ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………..…………….... [1] [Total: 20]

6 © VJC 2024 9729/02/PRELIM/24 2 (a) The reaction between iron(III) ions, Fe3+(aq), and iodide ions, I–(aq), occurs as shown. Fe3+(aq) + I–(aq) → Fe2+(aq) + 1 2I2(aq) The rate of this reaction can be followed by the change in the I–(aq) concentration as given in the graph in Fig. 2.1. The initial concentration of Fe3+(aq) is 0.150 mol dm–3. Fig. 2.1 (i) Use Fig. 2.1 to calculate the initial rate of reaction and the rate of reaction at 20 s. Show your working on the graph. [2]

7 © VJC 2024 9729/02/PRELIM/24 [Turn over (ii) Hence, determine the order of reaction with respect to the concentration of iodide ions. Show your working. [1] (iii) Explain why it is important that the concentration of Fe 3+(aq) is in large excess compared to the concentration of I–(aq) in this experiment. ………………………………………………………………………………………………….... ………………………………………………………………………………………………….... ………………………………………………………………………………..…………….... [1] (iv) It is found that the reaction is first order with respect to the concentration of Fe 3+(aq). Write the rate equation for the reaction between Fe3+(aq) and I–(aq). ………………………………………………………………………………..…………….... [1] (v) Use the rate equation and the initial rate you have determined in (a)(i) to calculate the rate constant, stating the units. [2] (vi) A new experiment of the same reaction was carried out at a different temperature. The value of the rate constant was found to be 2.10. Deduce whether the new experiment was carried out at a higher or lower temperature than the original experiment. ………………………………………………………………………………………………….... ……………