Question

Aluminium oxide may be electrolysed at 1000⁰C to furnish aluminium metal (At.Mass of Al = 27 amu ; 1 Faraday

= 96,500 Coulombs). The cathode reaction is

$\text{A}\text{l}^{\text{3+}}\text{ + 3}\text{e}^{-} \rightarrow \text{A}\text{l}^{0}.$ To prepare 5.12 kg of aluminium metal by this method, one would require :

• A. 5.49 × 107 C of electricity
• B. 1.83 × 107 C of electricity
• C. 5.49× 104 C of electricity
• D. 5.49 × 1010 C of electricity

Answer 1

Answer: (A)

5.49 × 107 C of electricity

Answer 2

$\mathrm { Al } ^ { 3 + } + 3 \mathrm { e } ^ { - } \longrightarrow \mathrm { Al }$ $\frac{\text{5.12} \times \text{1}\text{0}^{3}}{27}\text{=189.62 mol.}$ Charge = 189.62 × 3 × 96500 = 5.489 × 107 coulomb