Question

Purification of copper can be achieved by electrorefining copper from an impure copper anode onto a pure copper cathode in an electrolytic cell. How many hours will it take to plate 12.0 kg of copper onto the cathode if the current passed through the cell is held constant at 41.0 A? Assume the copper in the electrolytic solution is present as Cu2 .

Answer 1

Molar mass of copper = 63.546 g/mol

12.0 kg = 12000 / 63.546 = 188.84 moles

Each mole of Cu²⁺ requires 2 moles of electrons to get reduced .

So 188.84 moles of copper would require 2 x 188.84 = 377.68 moles of electrons

1 mole of electrons require 96485 Coulombs of charge

So 377.68 moles of electrons would require = 377.68 x 96485 = 36440454.8 coulombs

Q = I. t

where Q is charge , i is current and t is time

So putting all the values we get

36440454.8 = 41.0 x t

t = 888791.6 seconds

or 10.29 days