Chemistry - Redox Reactions Question with Solution | TestHub

Calculate the amount (in mg) of $\mathrm{Se}{\mathrm{O}}_3^{2-}$ in solution on the basis of the following data: 20 ml of M/20 solution of $\mathrm{KBr}{\mathrm{O}}_3$ was added to a definite volume of $\mathrm{Se}{\mathrm{O}}_3^{2-}$ solution. The bromine evolved was removed by boiling and excess of $\mathrm{KBr}{\mathrm{O}}_3$ was back titrated with 15 ml of M/25 solution of $\mathrm{NaAs}{\mathrm{O}}_2$. The reactions are $\mathrm{Se}{\mathrm{O}}_3^{2-}$ + $\mathrm{Br}{\mathrm{O}}_3^{-}$ + ${\mathrm{H}}^{+}$ $\to$ $\mathrm{Se}{\mathrm{O}}_4^{2-}$ + $\mathrm{B}{\mathrm{r}}_2$ + ${\mathrm{H}}_2\mathrm{O}$; $\mathrm{Br}{\mathrm{O}}_3^{-}$ + $\mathrm{As}{\mathrm{O}}_2^{-}$ + ${\mathrm{H}}_2\mathrm{O}$ $\to$ $\mathrm{B}{\mathrm{r}}^{-}$ + $\mathrm{As}{\mathrm{O}}_4^{3-}$ + ${\mathrm{H}}^{+}$ (Se = 79)