Question

How long will it take to plate out each of the following with a current of 150A?

a. 300g of Au from Au⁺³

b. 2.75 moles of Cr from Cr⁺⁶

c. 3 g of Fe from Fe⁺²

d. 2 pounds of Zn from Zn +2

Answer 1

Au⁺³ + 3e ---------> Au

According to above equation we require 3 moles of electrons or 3 F of charge to deposit one mole 197g of gold.

F = faraday = 96487C

300g will require (3 / 197) X 300 = 4.57 F

charge = current X time

4.57 X 96487 = 150 X t

t = 2939.64 s

b) Cr⁺⁶ + 6e ------> Cr

one mole of Cr require 6F

2.75 will require 2.75 X 6 = 16.5 F

16.5 X 96487 = 150 X t

t = 10613.57 s

c) Fe⁺² + 2e -----> Fe

2F are required to deposit one mole or 56g of Fe

3g will require (2 / 56) X 3 = 0.107 F

0.107 X 96487 = 150 X t

t = 68.82 s

d) Zn⁺² + 2e -----> Zn

2F are required to deposit 1 mole or 65g of Zn

2 pounds or 907g will require (2 / 65) X 907 = 27.9F

27.9 X 96487 = 150 X t

t = 17964.6 s