2020 YIJC Prelim P4 QP

1 YIJC [Turn over YISHUN INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION CANDIDATE NAME CLASS DATE H2 CHEMISTRY 9729/04 Paper 4 Practical Paper Thursday 25 August 2020 2 hours 30 minutes Candidates answer on question paper. No Additional Materials are required READ THESE INSTRUCTIONS FIRST This document consists of 18 printed pages and 2 blank pages. Write your name and class in the spaces at the top of this page. Give details of the practical shift and laboratory where appropriate, in the boxes provided. 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. You may lose marks if you do not show your working or if you do not use appropriate units. Qualitative Analysis Notes are printed on pages 18 and 19. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s use 1 22 2 19 3 14 Total 55 Shift Laboratory

2 YIJC [Turn over Answer all the questions in the spaces provided. 1 To determine the relative atomic mass of an unknown Group 1 element and the concentration of sulfuric acid solution using a graphical method FA 1 is a solution of sulfuric acid FA 2 is 0.550 moldm3 sodium hydroxide, NaOH FA 3 is solution of unknown Group 1 carbonate, M2CO3 FA 4 is methyl orange indicator Both the Group 1 carbonate and sodium hydroxide are bases which will neutralise sulfuric acid. M2CO3 + H2SO4  M2SO4 + CO2 + H2O 2NaOH + H2SO4  Na2SO4 + 2H2O In this experiment, you will add different volumes of FA 3 to identical samples of dilute sulfuric acid, FA 1. In each case, the amount of the Group 1 carbonate solution you add will only partially neutralise the sulfuric acid. You will then complete the neutralisation of each mixture by titration with s odium hydroxide, FA 2. Each titration is to be performed once only, so great care should be taken that you do not overshoot the end-points. Graphical analysis of your results will enable you to determine the relative atomic mass of the Group 1 element, and the concentration of the sulfuric acid solution. (a) Preparation of titration mixtures Prepare four different mixtures of FA 1 and FA 3 as described below. Mixture 1 1. Pipette 25.0 cm3 of FA 1 into a conical flask. 2. Fill a burette with FA 3. 3. Add 6.00 cm3 of FA 3 into the same conical flask. 4. Thoroughly stir the mixture and set it aside for later use. Mixture 2 Repeat the procedure used for Mi