Question

The amount of \(\mathrm{I}_{3}{ }^{-}(a q)\) in a solution can be determined by titration with a solution containing a known concentration of \(\mathrm{S}_{2} \mathrm{O}_{3}{ }^{2-}(a q)\) (thiosulfate ion). The determination is based on the net ionic equation

$$ \mathbf{2 S}_{2} \mathbf{O}_{3}^{2-}(a q)+\mathbf{I}_{3}^{-}(a q) \rightarrow \mathbf{s}_{4} \mathbf{O}_{6}^{2-}(a q)+3 \mathbf{I}^{-}(a q) $$

Given that it requires \(34.3 \mathrm{~mL}\) of \(0.360 \mathrm{M} \mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}(a q)\) to titrate a \(30.0-\mathrm{mL}\) sample of \(\mathrm{I}_{3}^{-}(\mathrm{aq})\), calculate the molarity of \(\mathrm{I}_{3}^{-}(\mathrm{aq})\) in the solution.

Answer 1