Determine the current (in A) to produce 4.20 g Ag when Ag⁺(aq) is electrolyzed for 2.00 h. (F = 96,500 C/mol)

Answer 1

Current is usually given in amps. Amps is also equivalent to coulombs / sec (C/s).

Equation:

Ag⁺(aq) + e- ==>Ag(s)

moles of Ag = 4.20 g Ag x 1 mol Ag / 107.9 g = 0.0389 moles Ag

moles e- = 0.0389 mols Ag x 1 mol e- / mol Ag = 0.0389 moles of electrons needed

1 mole electrons = 96,500 coulombs (C)

0.0389 moles e- x 96.500 C / mol e- = 3756 C needed

Converting 2.00 h to seconds, we have

2.00 hr x 60 min / hr x 60 sec / min = 7200 sec.

Current needed = 3756 C / 7200 s = 0.522 C/s = 0.522 amps

(be sure to check the math)