"To save on production costs, most automobile bumpers are never coated with more than 200 g of chromium. Determine how much time a standard bumper should be immersed in a chromium vat."

Question

This is what I have so far-

96,485 coulombs are required to plate 1 Cr; 52/6 = 8.67g.

To plate 200g:
96.485 * (200/8.67) = 96.485 * 23.068 C = 2,225.721 coulombs
1 A = 1 C/s
(amperes) x (time) = 2,225.721 coulombs.

I know this may seem stupid but I can't seem to remember how to determine amps. Please help.

Answer 1

I believe you should have divided 52 by 3; the electroplating probably goes from Cr^3+ to Cr which is a change of 3 electrons.
Then coulombs needed = 96,485 x (200/17.3) = ?
C = amps x seconds but you have two unknowns. You don't know amps (usually given in the problem) or seconds (which is what the problem is asking).

Answer 2

Ahh thank you - so then there would be 8346.453 coulombs needed instead of 2225.721.

As there are two unknowns, I cannot solve this problem any further... this is for an assignment due tomorrow, what should I do?

Answer 3

Sorry that should say 1115433.526 coulombs, not 8346.453.