2022 TJC Prelims H2 Paper 2 Structured QP

9729 / TJC Prelims / 2022 DO NOT WRITE IN THIS MARGIN [Turn over TEMASEK JUNIOR COLLEGE 2022 JC2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CENTRE NUMBER S INDEX NUMBER Chemistry 9729/02 Paper 2 Structured Questions 25 August 2022 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your Centre number, index number and name 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 the questions in the spaces provided on the Question Paper. 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. This document consists of 23 printed pages and 1 blank page. For Examiner’s Use Paper 1 /30 Paper 2 Q1 /9 Q2 /14 Q3 /10 Q4 /8 Q5 /20 Q6 /14 Total /75 Paper 3 /80 TOTAL (%) /100

2 DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelims / 2022 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN Answer all the questions in the space provided. 1 (a) Element W is from Period 5 of the Periodic Table. The first eight ionisation energies of element W, in kJ mol-1, are 869 1800 2690 3610 5720 6670 12000 13800 (i) Identify element W and explain your answer. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... .................................................................................................................................. [2] (ii) Explain the difference between the first ionisation energy of element W compared to the element to its left on the Periodic Table. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... .................................................................................................................................. [2]

3 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelims / 2022 DO NOT WRITE IN THIS MARGIN [Turn over (b) The chlorides of elements in Period 3 of the Periodic Table show different behaviours on addition to water. (i) Describe and explain the reactions of aluminium chloride, A lCl3, and phosphorus pentachloride, PCl5, with excess water. Write equations for any reactions that occur. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... .................................................................................................................................. [3] (ii) The reaction of PCl5 with limited amount of water involves step -wise substitution of –Cl with –OH. Write the overall balanced equation for the reaction of PC l5 with limited amount of water. Hence, suggest a three-step reaction sequence for this reaction. Overall equation: .......................................................................................................... Step 1: .......................................................................................................................... Step 2: .......................................................................................................................... Step 3: .......................................................................................................................... [2] [Total: 9]

4 DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelims / 2022 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 2 Boron trifluoride, BF3, and aluminium fluoride, AlF3, differ markedly in their physical properties. compound melting point / C BF3 –127 AlF3 1291 (a) (i) State the type of bonding present in each of these compounds and draw ‘dot-and-cross’ diagrams in the boxes below to illustrate this bonding. Type of bonding: …………………………. Type of bonding: …………………………. BF3 AlF3 [2] (ii) Outline the principles of the Valence Shell Electron Pair Repulsion theory. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... .................................................................................................................................. [2]

5 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelims / 2022 DO NOT WRITE IN THIS MARGIN [Turn over (iii) Boron trifluoride forms a compound with ammonia. Use the Valence Shell Electron Pair Repulsion theory t