1.

Indicatethe principlebehindthemethodused from refiningof zinc ?

Answer»

SOLUTION :Zinc is refinedbyelectrolyticrefiningwhich is basedupon teprincipleofoxidation-reduction. In thismethod,the impure metalis madethe anode whilethecathodeconsists of astrip ofpure zinc metal. Theseelectrodesare suspendedin an electrolyticbathcontaininga solutionof`Zn SO_ 4`acidifiedwithdil. ` H_ 2 SO_ 4`.Whenelectriccurrent is passed , zincmetalionsfrom theelectrolyte solutionare deposited atthe cathodein formof pure metalwhile an equivalentamount of zinc metaldissolvefrom the anodeand goes into theelectrolyte solution as zinc metalions, i.e.,
Anode:` Zn (s)toZn^(2 +)(aq)+2 e ^(-) `
CATHODE :` Zn^( 2 +)(aq) toZn (s) `
Theimpurities ofless BASIC metals such as iron, cadmium, arsenicand antimonyusually associated withinpure zinc, HOWEVER, settledownunder the anodeas anode mud.


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