$\mathrm{Fe}^{3+}$ is reduced to $\mathrm{Fe}^{2+}$ by using\

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Professor PC Thomas Classes · Answer

(a, b) : (a) $\mathrm{H}_{2} \mathrm{O}_{2}$ in alkaline medium reduces $\mathrm{Fe}^{3+}$ to $\mathrm{Fe}^{2+}$.\ $2 \mathrm{Fe}_{(a q)}^{3+}+\mathrm{H}_{2} \mathrm{O}_{2(a q)}+2 \mathrm{OH}_{(a q)}^{-}$ $ightarrow 2 \mathrm{Fe}_{(a q)}^{2+}+\mathrm{O}_{2(g)}+2 \mathrm{H}_{2} \mathrm{O}_{(l)}$\ (b)$\mathrm{Na}_{2} \mathrm{O}_{2}$ in water,\ $\mathrm{Na}_{2} \mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O} ightarrow 2 \mathrm{NaOH}+\mathrm{H}_{2} \mathrm{O}_{2}$\ $\left(\mathrm{H}_{2} \mathrm{O}_{2}ight.$ in alkaline medium reduces $\mathrm{Fe}^{3+}$ to $\mathrm{Fe}^{2+}$ )\ (c)$\mathrm{H}_{2} \mathrm{O}_{2}$ in acidic medium oxidises $\mathrm{Fe}^{2+}$ to $\mathrm{Fe}^{3+}$.\ $2 \mathrm{Fe}_{(a q)}^{2+}+\mathrm{H}_{2} \mathrm{O}_{2(a q)}+2 \mathrm{H}_{(a q)}^{+} ightarrow 2 \mathrm{Fe}_{(a q)}^{3+}$\ $+2 \mathrm{H}_{2} \mathrm{O}_{(l)}$\ (d)$\mathrm{Na}_{2} \mathrm{O}_{2}$ in presence of $\mathrm{H}_{2} \mathrm{SO}_{4}$, $\mathrm{Na}_{2} \mathrm{O}_{2}+\mathrm{H}_{2} \mathrm{SO}_{4} ightarrow \mathrm{Na}_{2} \mathrm{SO}_{4}+\mathrm{H}_{2} \mathrm{O}_{2}$\ (Neutral medium)\ In alkaline medium, reducing action of $\mathrm{H}_{2} \mathrm{O}_{2}$ is more effective.\