Question

Copper is plated onto the cathode of an electrolytic cell containing CuCl2(aq). How long does it take to plate 121 mg of copper with a current of 4.0 A ?

Answer 1

Electrolysis equation is:
Cu2+   +   2e-    ------> Cu

1 mol of Cu requires 2 mol of electron
1 mol of electron = 96485 C
So,1 mol of Cu requires 192970 C

let us calculate mol of element deposited:
use:
number of mol, n = mass/molar mass
= 0.121/63.55
= 0.0019 mol


total charge = mol of element deposited * charge required for 1 mol
= 0.0019*192970
= 367.4173 C
use:
time = Q/i
= 367.4173/4
= 91.8543 seconds
= 91.8543/60 min
= 1.53 min
Answer: 1.53 min

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