2022 RVHS JC2 H2 CM Prelim P2 (QP)

River Valley High School 9729/02/PRELIM/22 [Turn over 2022 Preliminary Examination RIVER VALLEY HIGH SCHOOL JC 2 PRELIMINARY EXAMINATION CANDIDATE NAME CLASS 2 1 J CENTRE NUMBER S INDEX NUMBER H2 CHEMISTRY 9729/02 Paper 2 Structured Questions 14 September 2022 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your Centre number, index number, class and name on all the work that you hand in. 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. DO NOT WRITE IN ANY BARCODES. Answer all questions in the spaces provided on the Question Paper. If additional space is required, you should use the pages at the end of this booklet. The question number must be clearly shown. 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 Question Number 1 2 3 4 5 Marks 9 17 14 14 21 significant figures units Total 75 This document consists of 20 printed pages.

2 River Valley High School 9729/02/PRELIM/22 2022 Preliminary Examination 1 Ammonium salts are typically used in instant cold packs. The cold pack contains water and an inner pouch containing an ammonium salt. A crushing action causes the inner pouch to break and release the salt, which quickly dissolves to lower the pack’s temperature. To determine whether ammonium nitrate or ammonium chloride is more effective as the cold pack ingredient, a student decided to conduct an experiment to find out the enthalpy changes of solution of the two salts. He first added ammonium nitrate to water and determined the tempe rature change by plotting a suitable graph to correct for heat transfer. In a preliminary investigation, the enthalpy change of solution of ammonium nitrate was found to be approximately +26.0 kJ mol–1. (a) Define the term enthalpy change of solution. ……………………..…………………………………………………........…….. ……………………..…………………………………………………................. ……………………..…………………………………………………........…….. [1] (b) (i) The student was told to use 50.0 cm3 of water to conduct the experiment. Suggest a minimum mass of ammonium nitrate that could be used to effect a temperature change of 5.0 °C. Justify your choice with relevant calculations. You should assume that 4.18 J of heat energy changes the temperature of 1.0 cm3 of solution by 1.0 °C. [1]

3 River Valley High School 9729/02/PRELIM/22 [Turn over 2022 Preliminary Examination (ii) The student carried out the following procedure to find the enthalpy change of solution of ammonium nitrate. 1. Weigh accurately about 4.00 g of ammonium nitrate in a weighin