2. How many moles of electrons are required for the complete reduction of 20 mL of a 0.5 M solution — Electrochemistry Chemistry Question

💡 Solution & Explanation

Moles of $KMnO_4$ = Molarity $\times$ Volume(L) = $0.5 \times 20 \times 10^{-3} = 10^{-2}$ mol. In acidic medium, $Mn^{7+} + 5e^- \rightarrow Mn^{2+}$. 1 mol $KMnO_4$ requires 5 moles of electrons. So, $10^{-2}$ mol requires $5 \times 10^{-2} = 0.05$ moles of electrons.