Question

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

• A. 180 kg
• B. 270 kg
• C. 540 kg
• D. 90 kg

Answer 1

Answer: (D)

(d) In Hall and Heroult process,
$2 Al_2O_3 + 4C \rightarrow 4 Al + 2CO_2 + 2CO$
but for the removal of only C 02, following equation is possible.
$2 Al_2 O_3 + 3C \rightarrow 4 Al + 3CO_2 $
$_{=36}^{3 \times 12} \, \, \, \, \, \, _{=108}^{4 \times 27}$
$\therefore $ For 108 g of Al, 36 g of C is required in above reaction.
$\therefore $ For $270 \times 10^3$ g of Al required amount of C
$\frac {36}{108} \times 270 \times 10^3 $
$= 90 \times 10^3 g = 90 \, kg$