Magnesium metal is manufactured industrially by the electrolysis of molten MgCl
CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
Magnesium metal is manufactured industrially by the electrolysis of molten MgCl2. In a particular plant, a current of 8.00 × 104 A is passed through the molten salt for 20.0 h. Only 84.0 % of the charge that enters the cell actually produces magnesium; the remainder is consumed by competing processes. The half-reaction at the cathode is
Mg2+(l) + 2 e− → Mg(l)
Assume the density of impurities is negligible and the Faraday constant is 96 485 C mol−1.
(a) Calculate the total charge delivered by the power supply during the 20.0 h run.
(b) Determine the number of moles of electrons that actually participate in magnesium production, taking into account the 84.0 % current efficiency.
(c) Using your answer to part (b), calculate the theoretical mass of magnesium that should be produced.
(d) Give one operational adjustment the plant could implement to increase current efficiency, and explain chemically how this adjustment would reduce the loss of charge to side processes.