Tamilnadu BoardEnglish MediumSTD 12ChemistryMetallurgy3 Marks
Question
Write a short note on electrochemical principles of metallurgy.
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Answer
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; $Cu _{( aq )}^{2+}+ Zn _{( s )} \longrightarrow Cu _{( s )}+ Zn _{( aq )}^{2+}$
Zinc is more reactive than copper and displaces copper from its salt solution.
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