Question

A sample of a new cleaning product, "Joe's Famous Bleach Cleaner," with a mass of 42.0 g , was diluted with an acetic acid solution containing excess I−. A small amount of starch indicator solution was then added, turning the solution a deep bluish-purple. The solution was then titrated with 0.410 M sodium thiosulfate, Na2S2O3, containing the ion S2O32−. A volume of 41.0 mL of sodium thiosulfate, the titrant, was needed to turn the solution colorless. What is the percentage composition by mass of NaClO in the bleach product? Express your answer to three significant figures and include the appropriate units.