The number of moles of that will be needed to react with one mole of sulfite ion in acidic solution — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

**Reduction:** $MnO_4^- + 8H^+ + 5e^- \rightarrow Mn^{2+} + 4H_2O$ ($n=5$). <br>**Oxidation:** $SO_3^{2-} + H_2O \rightarrow SO_4^{2-} + 2H^+ + 2e^-$ ($n=2$). <br>Equating equivalents: $n_1 M_1 = n_2 M_2 \Rightarrow 5 \times (\text{moles } KMnO_4) = 2 \times (1 \text{ mole } SO_3^{2-})$. <br>Moles $KMnO_4 = 2/5$.