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General Principles and processes of Isolation of Elements
medium
In the leaching of alumina from bauxite, the ore expected to leach out in the process by reacting with $\mathrm{NaOH}$ is:
A
$\mathrm{TiO}_{2}$
B
$\mathrm{SiO}_{2}$
C
$\mathrm{Fe}_{2} \mathrm{O}_{3}$
D
$ZnO$
(JEE MAIN-2021)
Solution
In bauxite impurities of $\mathrm{Fe}_{2} \mathrm{O}_{3}, \mathrm{TiO}_{2}$ and $\mathrm{SiO}_{2}$ are present, $\mathrm{Fe}_{2} \mathrm{O}_{3}$ and $\mathrm{TiO}_{2}$ are basic oxides therefore does not reacts with or dissolve in $\mathrm{NaOH}$ whereas $\mathrm{SiO}_{2}$ is acidic oxide it gets dissolve in $\mathrm{NaOH}$, hence leach out
$\mathrm{SiO}_{2}+2 \mathrm{NaOH} \rightarrow \mathrm{Na}_{2} \mathrm{SiO}($ aq. $)+\mathrm{H}_{2} \mathrm{O}$
Standard 12
Chemistry