Commercial electrolytic cells for producing aluminum operate at 5 volts and 100,000 Amperes. How long does it take to produce 1000 kilograms of aluminum?
a. 1 x 10^15 seconds
b. 9 x 10^6 seconds
c. 7 x 10^3 seconds
d. 3.3 x 10^4 seconds
e. 1 x 10^5 seconds
One Response
This can be calculated from the following equatiom , derived by michael faraday
m = QM/(Fn)
where
m is the mass of the substance produced at the electrode (in grams), (1,000, 000)
Q is the total electric charge that passed through the solution (in coulombs),
n is the valence number of the substance as an ion in solution (electrons per ion), (+3)
F is Faraday’s constant, 96485 coulombs per mole
M is the molar mass of the substance -assumed to be aluminium oxide-(in grams per mole), 101.96 g/mol
Q=mFn/M= 1000000 *96485*3/101.96= 2838907415 coulombs
bur Q=I*t and t= Q/I = 2838907415/100000= 2.8389 x 10 ^4 , which is close to d