NJC 2022 H1 Chem Promo P2 Ans

NJC SH1 Promotional Examination 8873/02/2022 [Turn over NATIONAL JUNIOR COLLEGE SH1 Promotional Examination Higher 1 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 2 Structured Questions Candidates answer on the Question Paper. Additional Materials: Data Booklet 8873/02 29 September 2022 1 hour 30 minutes READ THE INSTRUCTIONS FIRST Write your subject class, registration number and name in the spaces at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams or graphs. Do not use paper clips, highlighters, glue or correction fluid. Answer all questions on the Question Paper. The use of an approved 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. Appropriate significant figures and units are expected for final numerical answers. For Examiner’s Use 1 /17 2 /9 3 /8 4 /15 5 /11 Penalty Presentation Paper 2 /60 Paper 1 /20 Total /80 Promo Percentage /100 This document consists of 21 printed pages and 3 blank pages.

2 NJC SH1 Promotional Examination 8873/02/2022 For Examiner’s Use 1 Some properties of SCl2, S2Cl2, S8 and Cl2 are shown in the table. property SCl2 S2Cl2 S8 Cl2 density / g cm−3 1.62 1.69 2.07 0.00290 melting point / C −78 −80 115 −102 boiling point / C decomposes at 59 C 137 445 −34 ∆Hfꝋ / kJ mol−1 −49.8 −59.4 (a) S2Cl2 can be made by direct combination of sulfur in its standard state, S8, and chlorine gas, Cl2. (i) Write a thermochemical equation that represents the standard enthalpy change of formation of S2Cl2. [2] ¼ S8 (s) + Cl2 (g) ⎯→ S2Cl2 (l) ∆Hfꝋ = −59.4 kJ mol−1 Correct species (in particular S8) and balanced eqn, with ∆Hfꝋ value Correct state symbols of all species (ii) A chemist wishes to prepare 10.0 cm3 of S2Cl2 from its elements. Use the data in the table to calculate the mass of sulfur required to produce this volume of S2Cl2. Give your answer to 4 significant figures. Mass of S2Cl2 = 1.69 g cm−3 × 10.0 cm3 = 16.9 g Amount of S2Cl2 = 16.9 / 135.2 = 0.125 mol Amt of sulfur, S8 = ¼ × 0.125 = 0.03125 mol Mass of sulfur, S8 = 0.03125 × (8 × 32.1) = 8.025 g (4 s.f.) [2]

3 NJC SH1 Promotional Examination 8873/02/2022 [Turn over For Examiner’s Use (iii) Suggest a reason for the difference in physical state of S 8 and C l2 at room temperature and pressure. [2] Both are non-polar simple covalent molecules. S8 has a