Triiodide ions are generated in solution by the following (unbalanced) reaction in acidic solution:

\[\mathrm{IO}_{3}^{-}(a q)+\mathrm{I}^{-}(a q) \longrightarrow \mathrm{I}_{3}^{-}(a q)\]

Triiodide ion is determined by titration with a sodium thiosulfate \(\left(\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}ight)\) solution. The products are iodide ion and tetrathionate ion \(\left(\mathrm{S}_{4} \mathrm{O}_{6}{ }^{2-}ight)\).

a. Balance the equation for the reaction of \(\mathrm{IO}_{3}{ }^{-}\)with \(\mathrm{I}^{-}\)ions.

b. A sample of \(0.6013 \mathrm{~g}\) of potassium iodate was dissolved in water. Hydrochloric acid and solid potassium iodide were then added in excess. What is the minimum mass of solid \(\mathrm{KI}\) and the minimum volume of \(3.00 \mathrm{M} \mathrm{HCl}\) required to convert all of the \(\mathrm{IO}_{3}{ }^{-}\) ions to \(\mathrm{I}_{3}{ }^{-}\)ions?

c. Write and balance the equation for the reaction of \(\mathrm{S}_{2} \mathrm{O}_{3}{ }^{2-}\) with \(\mathrm{I}_{3}{ }^{-}\)in acidic solution.

d. A \(25.00-\mathrm{mL}\) sample of a \(0.0100 \mathrm{M}\) solution of \(\mathrm{KIO}_{3}\) is reacted with an excess of KI. It requires \(32.04 \mathrm{~mL}\) of \(\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\) solution to titrate the \(\mathrm{I}_{3}{ }^{-}\)ions present. What is the molarity of the \(\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\) solution?

e. How would you prepare \(500.0 \mathrm{~mL}\) of the \(\mathrm{KIO}_{3}\) solution in part \(d\), using pure dry \(\mathrm{KIO}_{3}\) ?