Question

The significance of leaching in the extraction of aluminium is

• A. it helps removing the impurities like $Si{O}_2$, $F{e}_2{O}_3$, etc from the bauxite ore
• B. it converts the ore into oxide
• C. it reduces melting point of the ore
• D. it eliminates water from bauxite

Answer 1

Answer: (A)

Bauxite is the principal ore of aluminium. The impurities present in bauxite are $Si{O}_2$ , iron oxides and titanium oxide $\left(Ti{O}_2\right)$. $A{l}_2{O}_3$ is extracted out as sodium aluminate. The impurity, $Si{O}_2$ too dissolves forming sodium silicate. Other impurities are left behind. $A{l}_2{O}_3+2NaOH+3H_{2}O\to 2Na\left[Al(OH{)}_4\right]$ Thus, leaching is used to remove the impurities present