Question

help

How many minutes will it take to plate out 2.19 g of chromium metal from a solution of Cusing a current of 25 2 amps in an electrolyte coll? 161 806 242 209 434 Submit Rest

Answer 1

Given data:

Mass of Cr = 2.19 g

Current = 25.2 amp

Solution:

1. Moles of Cr (n):

n = Mass of Cr / Molar mass of Cr

n = 2.19 g / (51.9961 g/mol) = 0.04212 mol

2. Total charge (Q):

Q = nzF; Here, Q is total charge = ?, n is moles = 0.04212 mol, z is number of electron transferred = 3, F is Faradays' constant = 96485 C/mol.

Plug the values and solve for Q.

Q = (0.04212 mol) x 3 x (96485 C/mol) = 12192 C

3. Time (t) taken for the platting:

t = Q / I; Here, Q = 12192 C, I = 25.2 amp = 25.2 C/s

Plug the values and solve for t.

t = (12192 C) / (25.2 C/s) = 483.8 s  

1 min = 60 s

$\therefore$ t = 483.8 s x (1min / 60 s) = 8.06 min

Hence, the " 2^nd option 8.06 " is correct.