A sodium thiosulfate, Na2S2O3, solution has a concentration of 0.150 M. An end point for this titration occurs when 32.89 mL of the sodium thiosulfate solution reacts with 24.80 mL of I2 solution. What is the molar concentration of the I 2 solution? The unbalanced chemical reaction for these species is: Na2S2O3 + I2 → Na2 S4O6 + NaI