Alkali metals are prepared by electrolysis of their fused chlorides because of the following reasons:

⇒ The discharge potential of alkali metals is much higher than that of hydrogen.

⇒ Therefore, when the aqueous solution of any alkali metal chloride is subjected to electrolysis, H₂ instead of the alkali metal is produced at the cathode.

⇒ Therefore, to prepare alkali metals, electrolysis of their fused chlorides is carried out.

⇒ One more reason is that we cannot prepare alkali metals by the chemical reduction of their oxides because alkali metals are very strong reducing agents.

⇒ Even, they cannot be prepared by displacement reactions (one element is displaced by another). This is because these elements are highly electropositive (to lose electrons).

⇒ Neither can electrolysis of aqueous solutions be used to extract these elements. This is because the liberated metals react with water.

⇒ Hence, to avoid these difficulties, alkali metals are usually prepared by the electrolysis of their fused chlorides.