Q.How many faradays of electricity are required for the following reaction to occur: $\text{MnO}_4^{-} \rightarrow \text{Mn}^{2+}$

Electrolysis uses electrical energy from an external DC source to drive a non-spontaneous reaction — typically decomposing a stable compound into its elements — inside a device called an electrolytic cell. Electrolysing molten NaCl illustrates the pattern: Na⁺ ions migrate to the cathode and are reduced to Na(l) ($E^{o}=-2.71$ V), while Cl⁻ ions migrate to the anode and are oxidised to Cl2(g) ($E^{o}=-1.36$ V), giving an overall $E^{o}=-4.07$ V — confirming the reaction is non-spontaneous, exactly as expected, so a voltage greater than 4.07 V must be supplied. Oxidation still occurs at the anode and reduction at the cathode as in a galvanic cell, but the electrode SIGNS reverse: the cathode is negative and the anode positive, because the external supply is forcing electrons in rather than the reaction pushing them out. …