A current of 3.98 A is passed through a Pb(NO3)2 solution. How long, in hours, would this current have to be applied to plate out 4.70 g of lead?

Answer 1

1 amp = 1 C/sec

3.98 amp = 3.98 C/sec

Pb²⁺ + 2e- ==> Pb(s)

moles Pb = 4.70 g Pb x 1 mol / 207 g = 0.0227 moles Pb

moles electrons = 0.0227 mols Pb x 2 mols electrons / mol Pb = 0.0454 mols electrons

1 mol electrons = 96,485 C

Coulombs needed = 0.0454 mols Pb x 96,485 C/mol = 4,381 C

Seconds needed = 4381 C x 1 sec / 3.98 C = 1101 sec

Hours needed = 1101 sec x 1 min / 60 sec x 1 hr / 60 min = 0.306 hours