Question

In Halls process,

• A. bauxite ore is fused with $NaOH$
• B. ammonia is prepared
• C. $A{l}_2{O}_3\cdot 2H_{2}O$ is fused with $NaHC{O}_3$
• D. bauxite ore is fused with $N{a}_{2}C{O}_3$

Answer 1

Answer: (D)

In Halls process, bauxite ore is fused with $N{a}_{2}C{O}_3$ to form sodium metaaluminate, $NaAl{O}_2$ which reacts with water, to precipitate $Al{(OH)}_3$ followed by filtration and heating to get pure alumina $(A{l}_2{O}_3)$ $A{l}_2{O}_3\cdot 2H_{2}O+N{a}_{2}C{O}_3\to 2NaAl{O}_2+C{O}_2+2H_{2}O$ $2NaAl{O}_3+3H_{2}O+C{O}_2\stackrel{333K}{\to }$ $2Al{(OH)}_3\downarrow N{a}_{2}C{O}_3$ $2Al{(OH)}_3\stackrel{1473K}{\to }A{l}_2{O}_3+3H_{2}O$