Sodium thiosulfate, Na2S2O3, is an important reagent for titrations. Its solutions can be standardized by titrating the iodine released when a weighed amount of potassium hydrogen iodate, KH(IO3)2 (389.912 g/mol), is allowed to react with excess potassium iodide in acidic solutions. The net ionic equations are:

productionofiodinefromKH(IO ) : IO +5I +6H+ 3I +3H O 32322

titrationofiodine: I +2S O 2 2I +S O 2 22346

What is the molarity of a sodium thiosulfate solution if 35.31 mL are required to titrate the iodine released from 0.1744 g of KH(IO3)2?