Q.Write a short note on electrochemical principles of metallurgy.

Step 1. Alongside the thermodynamic (Ellingham-diagram) principles used to pick a chemical reducing agent, electrochemical principles find their own, complementary application in metallurgy -- specifically for metals whose oxides are too thermodynamically stable for any ordinary chemical reducing agent (like carbon) to reduce, such as the active metals sodium and potassium.

Step 2. For such metals, the metal salt is taken in fused (molten) or dissolved form, and the metal ion is reduced either by treating it with a suitable chemical reducing agent, or -- far more commonly for these reactive metals -- by ELECTROLYSIS.

Step 3. The governing relation is ΔG0 = -nFE0, where n is the number of electrons transferred in the reduction, F is the Faraday constant, and E0 is the standard electrode potential of the redox couple. Because ΔG0 = -nFE0, a POSITIVE E0 corresponds to a NEGATIVE ΔG0, meaning the reduction is spontaneous -- so an electrochemical extraction is deliberately designed so that the net e.m.f. of the overall redox reaction comes out positive. …

Summarise Section 1.5's electrochemical framework (ΔG0=-nFE0, positive E0 -> spontaneous reduction), its use for the most reactive metals, its link to ordinary displacement reac …

• Treating 'electrochemical principles' as relevant only to the Hall-Heroult process specifically -- the underlying ΔG0=-nFE0 principle is more general, and also explains ordinary metal-displacement/cementation reaction …