Question

The significance of leaching in the extraction of aluminium is:

• A. it helps to remove 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)

it helps to remove the impurities like $Si{O}_2,F{e}_2{O}_3,$ etc from the bauxite ore

• Bauxite is the principal ore of aluminium. The impurities present in bauxite are $Si{O}_2$, iron oxides and titanium oxide ($Ti{O}_2$).
• $A{l}_2{O}_3$ is extracted out as sodium aluminate. The impurity, $Si{O}_2$ too dissolves forming sodium silicate. Other impurities are left behind.
  

$A{l}_2{O}_3+2NaOH+3H_{2}O\to 2Na\left[Al\right(OH{)}_4]$

• Thus, leaching is used to remove the impurities present and hence option $A$ is the correct option.