Some Basic Concepts of Chemistry - Result Question 49
####49. 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 (Atomic mass: $Al=27$ ) [2005]
(a) $270 kg$
(b) $540 kg$
(c) $90 kg$
(d) $180 kg$
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Solution:
(c) $2 Al_2 O_3+3 C \longrightarrow Al+3 CO_2$
Gram equivalent of $Al_2 O_3 \equiv$ g equivalent of $C$
Now equivalent weight of $Al=\frac{27}{3}=9$
Equivalent weight of $C$
$=\frac{12}{4}=3(\stackrel{0}{C} \to \stackrel{+4}{C} O_2)$
No. of gram equivalent of $Al=\frac{270 \times 10^{3}}{9}$
$ =30 \times 10^{3} $
Hence,
No. of gram equivalent of $C=30 \times 10^{3}$ Again,
No. of gram equivalent of $C$
$=\frac{\text{ mass in gram }}{\text{ gram equivalent weight }}$
$\Rightarrow 30 \times 10^{3}=\frac{\text{ mass }}{3}$
$\Rightarrow$ mass $=90 \times 10^{3} g=90 kg$
