ACJC 2026 Prelim P3 QP

This document consists of 23 printed pages and 1 blank page. Anglo-Chinese Junior College JC2 Chemistry Preliminary Examinations Higher 2 CANDIDATE NAME FORM CLASS INDEX NUMBER SUBJECT TUTOR CHEMISTRY Paper 3 Structured Questions You must answer on the question paper. 9476/03 01 September 2026 2 hours You will need: Data Booklet INSTRUCTIONS • Section A: answer all questions. • Section B: answer one question. • Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. • Write your name, centre number and index number in the boxes at the top of the page. • Write your answer to each question in the space provided. • Do not use an erasable pen. Do not use correction fluid or tape. • Do not write on any bar codes. • You may use an approved calculator. INFORMATION • The total mark for this paper is 75. • The number of marks for each question or part question is shown in brackets [ ]. For Examiner’s Use Question Number Marks 1 (21 m) 2 (16 m) 3 (18 m) 4 / 5 (20 m) Presentation of answers Total: 75

2 ACJC2026 9476/Preliminary Examinations/2026 [Turn over Section A Answer all the questions in this section. 1 (a) A kinetics investigation for the reaction of the halogenoalkanes K, L and M with NaOH(aq) at a particular temperature is carried out. State and explain the relative rate of reaction of K, L and M with NaOH(aq). ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………..[2] (b) (i) When K is reacted with sufficient ammonia and heated, a mixture of amine S, C4H11N, and a by-product T are obtained. Draw the structure of amine S. [1] K L M

3 ACJC2026 9476/Preliminary Examinations/2026 [Turn over (ii) Some tests were conducted on T. The observations are shown in Table 1.1. Table 1.1 Mr 277.5 addition of aqueous AgNO3 Immediate white precipitate formed Use the information in Table 1.1 to draw the structure of T. [1] (c) K can also undergo similar reaction in (b)(i) with sodium azide, NaN3, to form amine S. The intermediate formed in the process is an alkyl azide. (i) Use VSEPR theory to predict the C ‒Nx‒Ny bond angle in alkyl azide. Explain your answer. …………………………………………………………………………………………………… …………………………………………………………………………………………………… ………………………………………………………………………………………………….... ………………………………………………………………………………………………...…. …………………………………………………………………………………………………[2] alkyl azide

4 ACJC2026 9476/Preliminary Examinations/2026 [Turn over (ii) Draw a labelled diagram to show the orbitals that form the Nx‒Ny bond in the alkyl azide. [2] (iii) The azide ion, N3‒, consists of both σ and π bonds. Draw the ‘dot-and-cross’ diagram of the azide ion, N3 ‒ . [1] (d) (i) The azide ion, N 3− can be converted to the azide radical, •N3(g) under suitable conditions. Write an equation to represent the enthalpy change of formation of the azide radical, •N3(g). …………………………………………………………………………………………………[1] (ii) The bonding between the nitrogen atoms in the azide radical is similar to the alkyl azide. The enthalpy change of formation of the azide radical, •N3(g) is +452 kJ mol−1. Using data from the Data Booklet, calculate a value for the average bond energy of the nitrogen-nitrogen bond in an azide radical. [2]

5 ACJC2026 9476/Preliminary Examinations/2026 [Turn over (iii) Using your answer to (d)(i) and (ii), state the sign of entropy change of formation of azide radical. Hence, explain why the formation of azide radical from nitrogen does not occur readily at all temperatures. …………………………………………………………………………………………………… ………………………………………………………………………………………………….... ………………………………………………………………………………………………...…. …………………………………………………………………………………………………[2] (e) The Claisen-Condensation reaction involves the reaction of 2 esters to form a beta-keto ester, where a ketone group is formed at the second carbon away from the ester. An example of the Claisen -Condensation reaction is shown on Fig ure 1.2 when methyl ethanoate is used with a strong base. 2 beta-keto ester Figure 1.2 The first 2 steps for the mechanism for the reaction in Figure 1.2 are shown in Figure 1.3. step 1 step 2 Figure 1.3 (i) On Figure 1.3, complete the mechanism for step 2 by adding a lone pair of electrons, curly arrows and partial charges. [2] base base enolate ion enolate ion +

6 ACJC2026 9476/Preliminary Examinations/2026 [Turn over (ii) 1 mol of diester X was used in place of methyl ethanoate in the Claisen-Condensation reaction shown in Figure 1.2 to give 1 mol of Y, a cyclic compound, C5H6O3 and 1 mol of methanol. X Draw the structure of Y. [1] (f) The carbon‒oxygen bond lengths in propanone, methanol and the enolate ion shown in Figure 1.3 are analysed. (i) Describe how a covalent bond is formed. ………………………………………………………………………………………………...…. …………………………………………………………………………………………………[1] enolate ion propanone methanol

7 ACJC2026 9476/Preliminary Examinations/2026 [Turn over (ii) Compare the carbon -oxygen bond lengths in propanone, methanol, as well as the carbon-oxygen bond length of the Cx‒Oy bond in enolate. Rank these carbon‒oxygen bond lengths in ascending order and explain your answer. …………………………………………………………………………………………………… ………………………………………………………………………………………………….... ………………………………………………………………………………………………...…. …………………………………………………………………………………………………… ………………………………………………………………………………………………...…. …………………………………………………………………………………………………[3] [Total: 21]

8 ACJC2026 9476/Preliminary Examinations/2026 [Turn over 2 (a) Describe the reactions if any, of NaCl, AlCl3, and PCl5, with an excess of water.