Embibe Experts Solutions for Chapter: Redox Reactions, Exercise 3: EXERCISE-3

A $1.0 \mathrm{g}$ sample of ${\mathrm{Fe}}_2{\mathrm{O}}_3$ solid of $55.2\%$ purity is dissolved in acid and reduced by heating the solution with zinc dust. The resultant solution is cooled and made up to $100.0 \mathrm{mL}.$ An aliquot of $25.0 \mathrm{mL}$ of this solution requires $17.0 \mathrm{mL}$ of $0.0167 \mathrm{M}$ solution of an oxidant for titration. Calculate the number of moles of electrons taken up by the oxidant in the reaction of the above titration.

${\mathrm{KMnO}}_4$ oxidizes ${\mathrm{X}}^{\mathrm{n}+}$ ion to ${\mathrm{XO}}_3^{-},$ itself changing to ${\mathrm{Mn}}^{2+}$ in acid medium. $2.68\times {10}^{-3}$$\mathrm{mole}$ of ${\mathrm{X}}^{\mathrm{n}+}$ requires $1.61\times {10}^{-3}$ $\mathrm{mole}$ of ${\mathrm{MnO}}_4^{-},$ if the weight of $1 \mathrm{g}$ equivalent of ${\mathrm{XCl}}_{\mathrm{n}}$ is$56.$ Report the value of $\frac{\mathrm{X}}{\mathrm{n}},$ where $\mathrm{X}$ is the molar mass of ${\mathrm{X}}^{\mathrm{n}+}.$

Nitrous acid can act both as an oxidising as well as reducing agent.