Question

$KMn{O}_4$ acts as an oxidizing agent in acidic medium. The number of moles of $KMn{O}_4$ that will be needed to react with one mole of sulphide ions in acidic solution is:

• A. $\frac{2}{5}$
• B. $\frac{3}{5}$
• C. $\frac{4}{5}$
• D. $\frac{1}{5}$

Answer 1

The correct option is A $\frac{2}{5}$

$5\overline{e}+Mn{O}_4^{-2}⟶M{n}^{+2}\times 2+5^{-2}+2\overline{e}⟶S\times 2\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_2Mn{O}_4^{-}+5S^{-2}⟶2M{n}^{+2}+5S$

Divide reaction by $5.$

$\frac{2}{5}Mn{O}_4^{-}+5^{-2}⟶2M{n}^{+2}+5S$

Hence $1$ mole of sulphide ions will require $\frac{2}{5}$ moles of $Mn{O}_4^{-}$ ions.