Question

Write a short note on electrochemical principles of metallurgy.

Answer 1

• Reduction of oxides of active metals such as sodium, potassium etc. by carbon is thermodynamically not feasible.
• Such metals are extracted from their ores by using electrochemical methods.
• In this method the metal salts are taken infused form or in solution form.
• The metal ion present can be reduced by treating the solution with a suitable reducing agent or by electrolysis.
• Gibbs free energy change for the electrolysis is ∆G° = nFE°
  n = number of electrons involved in the reduction
  F = Faraday = 96500 coulombs
  E° = electrode potential of the redox couple.
• If E° is positive, is negative and the reduction is spontaneous.
• Hence a redox reaction is planned in such a way that the e.mi of the net redox reaction is positive.
  A more reactive metal displaces a less reactive metal from its salt solution.
  eg; \[\ce{Cu^{2+}_{(aq) } + Zn_{(s)} -> Cu_{(s)} + Zn^{2+}_{(aq) }}\]
• Zinc is more reactive than copper and displaces copper from its salt solution.