EJC Prelim H2 Chemistry Paper 2 QP

© EJC [Turn Over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examination 2025 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CIVICS GROUP 2 4 – INDEX NUMBER CHEMISTRY Paper 2 Structured Questions 9729/02 02 September 2025 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, civics group, index number 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 Paper 2 1 / 13 2 / 16 3 / 14 4 / 14 5 / 18 Total / 75 This document consists of 22 printed pages and 2 blank pages.

2 © EJC 9729/02/J2Prelim/25 1 Mount Ijen in East Java is famous for its rare blue flames, visible at night. The phenomenon occurs when sulfur vapour , from the volcano’s cracks burns, producing bright blue flames and sulfur dioxide. In the cool high -altitude air, some of the vapour condenses into solid sulfur. (a) A team of environmental chemists were authorised to collect solid sulfur deposits near Mount Ijen’s crater to investigate volcanic activity. The chemists burnt the sulfur sample and measured the temperature change for a fixed amount of water placed in a calorimeter. The data from their experiment is shown in Table 1.1. Table 1.1 mass of solid sulfur powder burnt /g 0.76 mass of water in beaker /g 150 initial temperature of water /oC 29.8 final temperature of water / oC 39.7 (i) Construct an equation to represent the standard enthalpy change of combustion of solid sulfur, S. ................................ ................................ ................................ ...................... [1] (ii) Calculate the enthalpy change of combustion of solid sulfur , S, based on their experiment. [2]

3 © EJC 9729/02/J2Prelim/25 [Turn Over (iii) During volcanic activity, many sulfur-containing gases such as hydrogen sulfide, H2S, and sulfur dioxide, SO2, are released. In the atmosphere, H2S can oxidise to form SO2, and subsequently sulfur trioxide, SO3, may be formed. H2S(g) + 3/2 O2(g) → SO2(g) + H2O(l) ∆Hr = –562 kJ mol–1 Use the data given in Table 1.2 to calculate the enthalpy change of combustion of solid sulfur, S. Table 1.2 compound ∆Hf / kJ mol–1 H2S(g) –20.6 H2O(l) –285.8 [2] (iv) Comment on the difference in values for the enthalpy change of combustion of solid sulfur determined in (a)(ii) and (a)(iii). ................................ ..............................