Aluminium oxide may be electorlysed at `1000^@C` to furnish aluminim metal (Atomic Mass `= 27 ` amu, `1 F = 96, 500 C)`. The cathode reaction is
`Al^3 + 3d^(-) rarr Al^@`
To prepare ` 5.12 kg` of aluminimu metal by this method woold require .

Options

A. `5.49xx10^(10)C`
B. `1.83xx10^(7)C`
C. `5.49xx10^(4)C`
D. `5.49xx10^(7)C`

Answer

d

Explanation

`Al_(2)O_(3)(` Molten`) overset(El ectrolysis)rarr 2Al^(3+)+3O^(2-)`
First method
`Al^(3+)+3e^(-) rarr Al`
`3F=3xx96500C=1mol `of `Al=27g `of `Al`
or
`27 g `of `Al =3xx96500C`
`5.12xx10^(3)g` of `Al=(3xx96500xx5.12xx10^(3))/(27)`
`=5.49xx10^(7)C`
Second methode
`1F=96500C`
`=1Eq` of `Al`
`=(27)/(3)g `of `Al=9g` `(n` factor for `All^(3+)=3)`
`:. 9g ` of `Al=96500C`
`5.12xx10^(3)g` of `Al=(96500xx5.12xx10^(3))/(9)`
`=5.49xx10^(7)C`