The balanced equation for the reaction of sulfite ion with permanganate ion in acidic…

CHEMISTRY · Single correct · A Level · Chemistry · Oxidation, reduction and redox reactions · Oxidation, reduction and redox reactions

Problem

The balanced equation for the reaction of sulfite ion with permanganate ion in acidic solution is

5\,\text{SO}_3^{2-}+2\,\text{MnO}_4^-+6\,\text{H}^+\rightarrow5\,\text{SO}_4^{2-}+2\,\text{Mn}^{2+}+3\,\text{H}_2\text{O}

Which of the following best explains why the coefficient in front of

\text{SO}_3^{2-}

is 5? (a) Charge balance can only be obtained on both sides of the equation when the coefficient of

\text{SO}_3^{2-}

is five. (b) Five

\text{SO}_3^{2-}

ions each lose two electrons, supplying the ten electrons needed to reduce two

\text{MnO}_4^-\,\text{ions}

\text{Mn}^{2+}

. (c) Each

\text{SO}_3^{2-}

ion loses one electron; five ions therefore provide enough electrons to match those gained by the permanganate ions. (d) Because sulfur is in the

+4

oxidation state in

\text{SO}_3^{2-}

, five such ions are needed so the total number of sulfur atoms is conserved.