A molten sample of MgCl₂ is electrolyzed at 910 °C in an industrial cell
CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
A molten sample of MgCl₂ is electrolyzed at 910 °C in an industrial cell. Faraday’s constant is F = 96 485 C mol⁻¹.
(a) Using the following standard reduction potentials, calculate ΔG° (in kJ mol⁻¹) for the formation of Mg(l) from Mg²⁺(l) at 910 °C.
Mg²⁺ + 2 e⁻ → Mg(l) E° = –2.37 V
Cl₂(g) + 2 e⁻ → 2 Cl⁻(l) E° = +1.36 V
(b) Determine the minimum magnitude of the applied cell potential that must be exceeded at 910 °C to make the overall electrolysis of molten MgCl₂ thermodynamically favorable. State any assumptions.
(c) If a constant current of 10.0 A is passed through the melt, calculate the minimum time (in minutes) required to produce exactly 1.00 g of Mg(l), assuming 100 % current efficiency.