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 15.0 kg of copper onto the cathode if the current passed through the cell is held constant at 34.5 A ? Assume the copper in the electrolytic solution is present as Cu 2 + .

Answer 1

Answer:

91hours

Explanation:

Firstly, we calculate the quantity of electricity passed.

Q = It

Q = 34.5t

Since we are dealing with cu2+

Cu2+ + 2e- ———> Cu

From the second law of electrolysis, 1 mole of copper ion will need 2 moles of electrons and thus would be needing half faraday of electricity.

Now one faraday would contain 96500C of electricity, 0.5F would contain = 48,250C of electricity .

The number of moles of copper thus deposited = 34.5t/48,250

We know that the mass of copper deposited equals no of moles of copper multiplied by its atomic mass

15kg = 34.5t/48250 * 64

15,000 * 48250 = 34.5t * 64

t = 327,785s

Converting this to hours means we divide by 3,600

327,785/3600 = 91hours