In an analytical determination of arsenic, a solution containing arsenious acid, H3AsO3, potassium iodide, and a small amount of starch is electrolyzed. The electrolysis produces free iodine from iodide ion, and the iodine immediately oxidizes the arsenious acid to hydrogen arsenate ion, HAsO42.
I2(aq) + H3AsO3(aq) + H2O(l) → 2I(aq) + HAsO4 2(aq) + 4H+(aq)
When the oxidation of arsenic is complete, the free iodine combines with the starch to give a deep blue color. If, during a particular run, it takes 65.4 s for a current of 10.5 mA to give an endpoint (indicated by the blue color), how many grams of arsenic are present in the solution?