Question

If 5 mg of Zn(s) is electrochemically deposited in the Daniell cell, how much charge should be passed through the cell assuming that there are not any parasitic reactions in the electrolysis.

Answer: 14.8C

Answer 1

Ans :

Number of mol of Zn = mass / molar mass

= ( 5x 10^-3 g) / ( 65.38 g/mol) = 7.65 x 10^-5 mol

Each mol of Zinc requires twice the number of mol of electrons

so number of mol of electrons = 2 x 7.65 x 10^-5 mol = 1.53 x 10^-4 mol

Each mol of electrons require 96485 C of charge

So 1.53 x 10^-4 mol electrons will require :

= 1.53 x 10^-4 x 96485

= 14.8 C