SJI 2021 Y4 Prelim Chemistry 6092 P3

1 ST JOSEPH’S INSTITUTION PRELIMINARY EXAMINATION 2021 (YEAR 4) CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY Paper 3 Additional Materials : Nil 6092/03 25 August 2021 1 hour 50 minutes READ THESE INSTRUCTIONS FIRST Write your name, class and index number on the cover page of this Question Paper. Write in dark blue or black fluid ink pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided. Candidates are reminded that all quantitative answers should include appropriate units. Candidates are advised to show all their working in a clear and orderly manner. The number of marks is given in brackets [ ] at the end of each question or part question. The use of an approved scientific calculator is expected, where appropriate. Shift Laboratory For Examiner’s Use Total / 40 This document consists of 9 printed pages including this cover page.

2 1 Read all the instructions carefully before starting the experiments in Question 1. Instructions You are going to carry out two experiments on two strong acids X and Y of the same concentration. (a) Experiment 1 Set up the apparatus as shown in the diagram below. Fill the plastic trough to about three-quarters full of water. Place the bee hive stand into the trough and insert the free end of the delivery tube through the bee hive stand. The other end of the delivery tube is connected to a rubber bung. Fill the 100 cm 3 measuring cylinder fully with water and cover the mouth of the cylinder with your palm. Invert the cyl inder into the trough of water and remove your hand, ensuring that there is minimal air in the measuring cylinder. Place the cylinder onto the bee hive stand , with the tip of the delivery tube in the mouth of the cylinder. Clamp the cylinder to a retort stand. Using a 50 cm3 measuring cylinder, measure 50 cm 3 of acid X. Pour it into the conical flask. Cut one of the strips of magnesium into four pieces . Ensure that the free end of the delivery tube is properly inserted into the measuring cylinder filled with water and place all four pieces of magnesium into the conical flask. Stopper the conical flask and s tart the stopwatch immediately, noting the volume of gas in the measuring cylinder at the same time. Swirl the contents of the flask and leave it to stand. In the table, record the volume of gas collected in the measuring cylinder eve ry 30 seconds for three minutes. time / s 0 30 60 90 120 150 180 [3]

3 (b) Experim