The amount of I3–(aq) in a solution can be determined by titration with a solution containing a known concentration of S2O32–(aq) (thiosulfate ion). The determination is based on the net ionic equation

Given that it requires 32.9 mL of 0.330 M Na2S2O3(aq) to titrate a 30.0-mL sample of I3–(aq), calculate the molarity of I3–(aq) in the solution.

1 answer

mols S2O3^2- = M x L = ?
mols I3^- = 1/2 that (look at the ionic equation)
M = mols I3^-/L I3^-