University of California, Davis CHEMISTRY 2C Titration-VERIFIED BY EXPERTS

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EXPERIMENT 5 REDOX TITRATION: TITRATION USING SODIUM THIOSULPHATE Objectives 1. To prepare a standard solution of potassium iodate for use to determine the concentration of sodium thiosulphate sol... ution accurately. 2. To acquire the proper techniques of carrying out a titration. Introduction Redox titrations using sodium thiosulphate as a reducing agent is known as iodometric titration since it is used specifically to titrate iodine. The reaction involved is: I2 + 2Na2S2O3 2NaI + Na2S4O6 I2 + 2S2O32- 2I- + S4O62- In this equation I2 has been reduced to I- :- 2S2O32- S4O62- + 2e I2 + 2e 2IThe iodine/thiosulphate titration is a general method for determining the concentration of an oxidising agent solution. A known volume of an oxidising agent is added into an excess solution of acidified potassium iodide. The reaction will release iodine:- Example: (a) With KMnO4 2MnO4- + 16H+ + 10I- 2Mn2+ + 5I2 + 8H2O (b) With KIO3 IO3- + 5I- + 6H+ 3I2 + 3H2O [Show More]

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