Aluminum metal is refined in a very energy-intensive process from bauxite ore using the Hall process, which requires electrolysis of aluminum oxide, Al2O3, in molten cryolyte at more than 1012°CIn an industrial electrolysis cell, 1900 kg of aluminum oxide was reduced with a current of 1500 ampsHow long did it take to reduce all the reactant to aluminum metal?Answer a.4000 hr b.660 hr c.1000 hr d.330 hr e.2000 hr
find moles using molar mass: (1,900,000 grams of aluminum oxide) / (101.96 g / mol) 18,635 mol of Al2O3 so, (18,635 mol of Al2O3) (2 mol Al / mol Al2O3) 37,270 mol Al since Al+3 3 e- - Al (37,270 mol Al) (3 mol e- / mol Al) 1.118 X 10^5 mol e- bouman.chem.georgetown.edu/S02/leCharge of 1 mole of electrons 96500 Coulombs (Faraday's constant, F) so, (1.118 X 10^5 mol e- mol e-) ( 96,500 Coulombs / mol e-) 1.079 X 10^10 Coulombs since Electrical current rate of passage of a charge units are Coulomb/sec an ampere 1500 amps 1500 Coulomb/sec so, (1.079 X 10^10 Coulombs) / (1500 Coulomb/sec) 7.193 X 10^6 sec ( 7.193 X 10^6 sec) (1 min / 60 sec) (1 hr / 60 min) 1998 hours your answer rounded to 2 sig figs sets your answer as e2000 hr
