Aluminium oxide may be electrolysed at 1000 $^{\circ}$C to furnish aluminium metal (Atomic mass = 27 amu: 1 faraday = 96,500 Coulombs). The cathode reaction is
$Al^{3+} + 3e^- \to Al^{\circ}$
To prepare 5.12 kg of aluminium metal by this method would require :