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Observe the following statements regarding purification of bauxite
I. During Hall's process, silica is removed as Si (vapour).
II. Bauxite ore contaminated with $\mathrm{Fe}_2 \mathrm{O}_3$ is purified in Baeyer's process.
III. During Serpeck's process, AlN is formed.
The correct answer is
Options:
I. During Hall's process, silica is removed as Si (vapour).
II. Bauxite ore contaminated with $\mathrm{Fe}_2 \mathrm{O}_3$ is purified in Baeyer's process.
III. During Serpeck's process, AlN is formed.
The correct answer is
Solution:
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Verified Answer
The correct answer is:
Only II and III are correct
Red bauxite which contains $\mathrm{Fe}_2 \mathrm{O}_3$ as the main impurity, is refined either by Baeyer's process or by Hall's process. White bauxite containing $\mathrm{SiO}_2$ impurity is refined by Serpeck's method. In Serpeck's method, following reactions take place.
$\begin{gathered}
\mathrm{Al}_2 \mathrm{O}_3 \cdot 2 \mathrm{H}_2 \mathrm{O}+3 \mathrm{C}+\mathrm{N}_2 \stackrel{1800^{\circ} \mathrm{C}}{\longrightarrow} 2 \mathrm{AlN}+3 \mathrm{CO}+2 \mathrm{H}_2 \mathrm{O} \\
\mathrm{AlN}+3 \mathrm{H}_2 \mathrm{O} \longrightarrow \mathrm{Al}(\mathrm{OH})_3+\mathrm{NH}_3 \\
2 \mathrm{Al}(\mathrm{OH})_3 \longrightarrow \mathrm{Al}_2 \mathrm{O}_3+3 \mathrm{H}_2 \mathrm{O}
\end{gathered}$
$\begin{gathered}
\mathrm{Al}_2 \mathrm{O}_3 \cdot 2 \mathrm{H}_2 \mathrm{O}+3 \mathrm{C}+\mathrm{N}_2 \stackrel{1800^{\circ} \mathrm{C}}{\longrightarrow} 2 \mathrm{AlN}+3 \mathrm{CO}+2 \mathrm{H}_2 \mathrm{O} \\
\mathrm{AlN}+3 \mathrm{H}_2 \mathrm{O} \longrightarrow \mathrm{Al}(\mathrm{OH})_3+\mathrm{NH}_3 \\
2 \mathrm{Al}(\mathrm{OH})_3 \longrightarrow \mathrm{Al}_2 \mathrm{O}_3+3 \mathrm{H}_2 \mathrm{O}
\end{gathered}$
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