Question

Al₂O₃ is reduced by electrolysis at low potentials and high currents. If 4.0 × 10⁴ amperes of current is passed through molten Al₂O₃ for 6 hours, what mass of aluminium is produced? (Assume 100% current efficiency. At mass of Al = 27 g mol^-1):

(a) 8.1 × 10⁴ g
(b) 2.4 × 10⁵ g
(c) 1.3 × 10⁴ g
(d) 9.0 × 10³ g

Answer 1

(a) 8.1 × 10⁴ g

Al³⁺ + 3e → Al

1 mol of Al = 27 g of Al is deposited by 3F or 3 × 96500 C of electricity.

Quantity of electricity passed