How is the method of extraction of metals high up in the reactivity series different from that for metal in the middle? Why the same process cannot be applied for them? Explain giving equations, the extraction of sodium.
The metals placed high up in the reactivity series (e.g., Na, K, Ca, Mg, Al) are highly reactive and strong reducing agents and are extracted by carrying out the electro-reduction of their molten salts. On the other hand, metals placed in the middle of the series (e.g., Fe, Zn, Cd, Co, Ni, etc.) are comparatively less reactive and are extracted by roasting or calcination. Sodium is extracted by electro-reduction process. NaCl ⇌ Na+ + Cl– Reaction at the cathode: Na+ + e+ → Na+ Reaction at the anode: Cl– – e– → Cl Cl + Cl → Cl2
