Faraday’s Law: Calculate Current or Time

Question

How many seconds are required to deposit 0.152 grams of nickel metal from a solution that contains Ni²+ ions, if a current of 0.586 A is applied.

_______s

Answer 1

1 A (amp) = 1 coulomb/sec (C/s)

If we can find the number coulombs required, we can find the seconds given a current of 0.586 C/s.

To do this, we will ultimately use Faraday's constant of 96,485 C/mole electrons

Ni²⁺ + 2e- ==> Ni(s) This is the equation for converting nickel ions into solid nickel

Note that for each mole of Ni(s) deposited, 2 moles of electrons are required.

Moles of Ni(s) desired = 0.152 g Ni x 1 mol Ni / 65.4 g = 0.00232 moles

Moles electrons needed = 0.00232 mol Ni x 2 mol e- / mol Ni = 0.00465 moles electrons

Converting this to coulombs, we have...

0.00465 moles electrons x 96,485 C / mole electrons = 448.7 C

Since we are using 0.586 A, which is equivalent to 0.586 C/s, we can now find the time, in seconds...

448.7 C x 1 s / 0.586 C = 766 seconds