Electrochemical Series Application

Whether one metal displaces another from solution is predicted by comparing standard reduction potentials, since the metal with the more negative potential is oxidised and displaces the metal with the more positive potential. Iron has E°(Fe^2+/Fe) = -0.44 V while copper has E°(Cu^2+/Cu) = +0.34 V. Because iron's potential is more negative, iron is more easily oxidised and will reduce Cu^2+ ions to copper metal: Fe + Cu^2+ → Fe^2+ + Cu. The standard cell potential for this displacement is E°_cell = 0.34 - (-0.44) = +0.78 V, and the positive value confirms spontaneity. The option of no reaction ignores the favourable potential difference. The claim that copper displaces iron reverses the reactivity order. Electrolysis is unnecessary because the reaction is already spontaneous. This is the classic NCERT displacement example demonstrating the electrochemical series. Understanding electrochemical series application in this way ties directly into the wider study of redox reactions and electrochemistry, where the same reasoning recurs across many problems. A common JEE pitfall is to ignore the role of displacement reaction, yet it is exactly this factor that distinguishes the correct answer from the tempting alternatives. Plausibility check: the observed deposition of reddish copper on an iron nail dipped in copper sulphate confirms the spontaneous reaction predicted by the positive E°_cell.