A solution of Na2S2O3 x 5H2O for titrating bleach. You use this solution to titrate 0.4901g of KIO3 solution (molar mass of KIO3=214.00g). 1 mol of KIO3 reacts with 6 moles Na2S2O3 x 5H2O. And 25.43 ml of Na2S2O3 x 5H2O reacts with the KIO3. What's the concentration of the thiosulfate solution?