Chapter 5, Problem 96RQ

Sodium nitrite, ${\text{NaNO}}_{\text{2}}$, is used as a preservative in meat products such as frankfurters and bologna. In an acidic solution, nitrite ion is converted to nitrous acid, ${\text{HNO}}_{\text{2}}$, which reacts with permanganate ion according to the equation

${\text{H}}^{\text{+}}+5{\text{HNO}}_{\text{2}}+2{\text{MnO}}_{\text{4}}{}^{\text{-}}\to 5{\text{NO}}_{\text{3}}+2{\text{Mn}}^{\text{2+}}+3{\text{H}}_{\text{2}}\text{O}$

A 1.000 g sample of a water-soluble solid containing ${\text{NaNO}}_{\text{2}}$ was dissolved in dilute ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ and titrated with $\text{0}\text{.01000 }M{\text{ KMnO}}_{\text{4}}$ solution. The titration required 12.15 mL of the ${\text{KMnO}}_{\text{4}}$ solution. What was the percentage by mass of ${\text{NaNO}}_{\text{2}}$ in the original 1.000 g sample?