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 11.5 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 Cu2+ .

Answer 1

Answer: 281 hours

Explanation:-

1 electron carry charge=$1.6\times 10^{-19}C$

1 mole of electrons contain=$6.023\times 10^{23}$ electrons

Thus  1 mole of electrons carry charge=$\frac{1.6\times 10^{-19}}{1}\times 6.023\times 10^{23}=96500C$

$Cu^{2+}+2e^-\rightarrow Cu$

$96500\times 2=193000Coloumb$ of electricity deposits 1 mole or 63.5 g of copper

0.0635 kg of copper is deposited by 193000 Coloumb

11.5 kg of copper is deposited by=$\frac{193000}{0.0635}\times 11.5=34952756$ Coloumb

$Q=I\times t$

where Q= quantity of electricity in coloumbs  = 34952756 C

I = current in amperes = 34.5 A

t= time in seconds = ?

$34952756 C=34.5A\times t$

$t=1013123sec=281hours$

Thus it will take 281 hours to plate 11.5 kg of copper onto the cathode if the current passed through the cell is held constant at 34.5 A.