CBSE Class 12-science Answered
Extractions of non-metal such as chlorine is based on oxidation.
A very common example of extraction based on oxidation is the extraction of chlorine from brine (chlorine is abundant in sea water as common salt).
2Cl–(aq) + 2H2O(l) → 2OH–(aq) + H2(g) + Cl2(g)
The ΔG0 for this reaction is + 422 kJ. When it is converted to E0 (using ΔG0 = – nE0F), we get E0 = – 2.2 V.
It will require an external e.m.f. that is greater than 2.2 V. But the electrolysis requires an excess potential to overcome some other hindering reactions. Thus, Cl2 is obtained by electrolysis giving out H2 and aqueous NaOH as byproducts.
Electrolysis of molten NaCl is also carried out. But in that case, Na metal is produced and not NaOH.