CHEM10003 Chapter Notes - Chapter 3: Sodium Thiosulfate, Polyiodide, Volumetric Flask
6 Jun 2017
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To determine the chemical formula of the polyiodide using analytical methods. Method: refer to first year chemistry laboratory manual page 57-59. Mass of beaker after sample has been transferred. Volume delivered in one aliquot of polyiodide: 5ml. Average volume of sodium thiosulphate required to reach endpoint: 4. 67 ml 0. 05. Number of moles of thiosulphate to reach endpoint: 9. 4 x 10-5 mol. Moles of iodine in one 5 ml aliquot: 4. 7x10-5 mol. Moles of iodine in original 50 ml sample: 4. 7x10-4 mol. Mass of iodine present in original sample: 0. 12 g. Percentage of iodine by mass in sample: 61. 04% Errors in results can be attributed to methodical errors in experimental procedure, particularly in transfer of iodine sample. Much mass was lost when transferring from the bag which ultimately. Furthermore, inaccuracy in reading and measurement when utilising the burette may also have contributed to any errors.
