JEE MAIN - Chemistry (2005 - No. 34)
Aluminium oxide may be electrolysed at 1000oC to furnish aluminium metal (Atomic
mass = 27 amu; 1 Faraday = 96,500 Coulombs). The cathode reaction is Al3+ + 3e- $$\to$$ Alo To prepare 5.12 kg of aluminium metal by this method would require
5.49 $$\times$$ 107 C of electricity
1.83 $$\times$$ 107 C of electricity
5.49 $$\times$$ 104 C of electricity
5.49 $$\times$$ 101 C of electricity
Explanation
$$1$$ mole of $${e^ - } = 1F = 96500\,C$$
$$27g$$ of $$Al$$ is deposited by $$3 \times 96500\,C$$
$$5120$$ $$g$$ of $$Al$$ will be deposited by
$$ = {{3 \times 96500 \times 5120} \over {27}}$$
$$ = 5.49 \times {10^7}C$$
$$27g$$ of $$Al$$ is deposited by $$3 \times 96500\,C$$
$$5120$$ $$g$$ of $$Al$$ will be deposited by
$$ = {{3 \times 96500 \times 5120} \over {27}}$$
$$ = 5.49 \times {10^7}C$$
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