Q26 / 155 · WBJEE 2019 · Chemistry
In the Bayer's process, the leaching of alumina is done by using
- A$\mathrm{Na}_{2} \mathrm{CO}_{3}$
- Correct answerBNaOH
- C$\mathrm{SiO}_{2}$
- D$\mathrm{CaO}$
Solution
In the Bayer's process, the leaching of alumina is done by using $\mathrm{NaOH}$.
$\mathrm{Al}_{2} \mathrm{O}_{3}(s)+2 \mathrm{NaOH}(a q) \stackrel{150^{\circ} \mathrm{C}, 35 \mathrm{atm}}{\longrightarrow} 2 \mathrm{Na}\left[\mathrm{Al}(\mathrm{OH})_{4}\right]+3 \mathrm{H}_{2} \mathrm{O}$
$2 \mathrm{Na}\left[\mathrm{Al}(\mathrm{OH})_{4}\right]+\mathrm{CO}_{2} \rightarrow \mathrm{Al}_{2} \mathrm{O}_{3} \cdot x \mathrm{H}_{2} \mathrm{O}+2 \mathrm{NaHCO}_{3}$
$\mathrm{Al}_{2} \mathrm{O}_{3} \cdot x \mathrm{H}_{2} \mathrm{O}(s) \underset{\longrightarrow}{\text{1470K}} \mathrm{Al}_{2} \mathrm{O}_{3}(s)+x \mathrm{H}_{2} \mathrm{O}(g)$
So, the option (b) is correct answer.
Hence, the correct answer is option: 'B'.