Question

Choose the correct option. How much 1C of electricity deposits?
A. 10.8 g of Ag
B. Electrochemical equivalent of Ag
C. Half of Electrochemical equivalent of Ag
D. 96500g of Ag

Answer 1

Hint: Students need to know and use Faraday’s First law of electrolysis and use the formula to solve the questions.

Complete step by step answer:
Electrolysis:- It is a phenomenon by which the elements are broken from their compounds and deposited at the electrodes. Cations are reduced at cathode and anions are oxidised at anion.

Faraday’s First law :- According to Faraday's first law the mass of an element deposited at an electrode during electrolysis is directly proportional to charge in coulombs passing through the solution.
$m\propto Q$
Q is charge in coulombs
${\displaystyle \frac{m}{Q}}=Z$
$Q={\displaystyle \frac{m}{Z}}$
Where Z is electro-chemical constant of the material used
Now when charge of 1 coulomb is passed through the solution in electrolysis, then, by using Faraday’s first law
Take, The molecular weight of silver (m)=108 (generally take silver (Ag) for this question)
$\therefore Z={\displaystyle \frac{m}{c}}$
After substituting the values of m=108 and C=1 in the above equation we get
$Z=108$
Therefore Z is the electrochemical equivalent of silver(Ag). From above calculation 1C of charge deposits 108 g of silver(Ag).

Hence from the above solution option B is correct.

Note:
While solving this question students generally forget the Faraday’s First law, its equation. They also don't know the molecular weight of elements and make errors while substituting the values. Students should remember the laws and molecular weights of the elements.