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Unformatted text preview: going to standardize a
freshly prepared solution of sodium thiosulfate (Na2S2O3). You will do this by reacting
iodate (IO3-) with excess iodide (I-) in acidic solution to produce a known quantity of
iodine and water. The iodine produced will be titrated with a sodium thiosulfate solution.
The products of the reaction between iodine and thiosulfate are the iodide ion and the
tetrathionate ion (S4O62-). By using a known amount of iodate and stoichiometric
calculations you are able to calculate the exact concentration of the thiosulfate solution
you have prepared.
In the second part of the experiment you will use your standardized thiosulfate solution to
analyze a bleach unknown. Bleach contains sodium hypochlorite (NaClO) that reacts
with iodide to produce iodine, chloride ion, and water. The amount of iodine produced
can then be determined by titration with your standard sodium thiosulfate.
As prelaboratory preparation, you should read sections the Redox sections in your text.
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- Spring '07