Chemical reaction of transformation of bauxite into alumina by Hall's process

Explanation

(i) In the Hall's process the ore is powderedand then leachedby heating with aqueous sodium carbonate to form water soluble sodium aluninate.
(ii) then the insoluble impurities are filtered out.
(iii) The filtrate is warmed and neutralised by passing carbon dioxide gas through it.
(iv) This results in the precipitation of aluminium hydroxide.
(v) `Al_(2)O_(3).2H_(2)O_((s))+NaCO_(2(aq)) to 2NaAlO_(2(aq)) to CO_(2(g))+ 2H_(2)O_((l))`
`2NaAlO_(2(aq))+3H_(2)O_((l))+CO_(2(g)) to 2Al (OH)_(3) darr +Na_(2)CO_(3)`
The precipitateof `Al(OH)_(3)` obtained in Hall's process is filtered, washed, dried and then calcinated by heating at `1000^(@)C` to obtain alumina.
(viii) `2Al(OH)_(3) to Al_(2)O_(3)+3H_(2)O`