Chemistry Question on General Principles and Processes of Isolation of Elements

Question

The mass of carbon anode consumed (giving only carbondioxide) in the production of $270\, kg$ of aluminium metal from bauxite by the Hall process is (Atomic mass $Al =27$ )

Answer 1

Solution

In Hall and Heroult process
$2 Al _{2} O _{3} \longrightarrow 4 Al +3 O _{2}$
$4 C +3 O _{2} \longrightarrow 2 CO _{2}+2 CO \uparrow$
$2 Al _{2} O _{3}+4 C \longrightarrow 4 Al +2 CO _{2}+2 CO$
Only for removal of $CO _{2}$ , following equation is possible

$\because$ For $108\, g$ of $Al , 36\, g$ of $C$ is required in above reaction
$\therefore$ For $270\, g$ of $Al$ require amount of $C$
$=\frac{36}{108} \times 270=90\, g$