Question

The electrochemical equivalent of a metal is\[3.3 \times {10^{ - 7}}kg/coulomb\]. The mass of the metal liberated at the cathode when a 3A current is passed for 2 seconds will be
A. \[19.8 \times {10^{ - 7}}kg\]
B. \[9.39 \times {10^{ - 7}}kg\]
C. \[6.6 \times {10^{ - 7}}kg\]
D. \[1.1 \times {10^{ - 7}}kg\]

Answer 1

Hint: In this, Faraday’s law of electrolysis will be used. According to this law, the quantity of mass of ions formed or discharged from electrolyte varies directly with the amount of electric current passed.
Formula Used: The formula used in this case will be
m=ZIt…….(i)
Where Z is the equivalent mass of the substance
‘t’ is the time taken
‘I’ is the current flowing
‘m’ is the mass of substance undergoing electrolysis

Complete Step by Step Answer:
Given that\[Z = 3.3 \times {10^{ - 7}}kg/coulomb\]
I = 3A
T = 2 seconds
Substituting the given values in equation (i) we get,
\[m = 3.3 \times {10^{ - 7}} \times 3 \times 2\]
\[m = 19.8 \times {10^{ - 7}}kg\]
Therefore, the mass of the metal liberated at the cathode will be\[19.8 \times {10^{ - 7}}kg\] .
Option A is the correct answer.

Note: Faraday’s laws of electrolysis was given by Michael Faraday in 1833. These laws give an idea on how much energy is transferred in electrolysis and how much is the substance deposited between the electrodes. Faraday’s laws of electrolysis have a wide range of applications these days. They are used in electrolysis to obtain non metals like hydrogen, fluorine, chlorine etc. It is also used to obtain renewable electricity. In electrolysis, electric energy is passed through a substance or a solution and the oxidation or reduction takes place. In oxidation and reduction, the substance loses or gains the electrons. It is a chemical reaction that is non spontaneous and breaks down a compound. The ions and the atoms are interchanged as addition or removal of the electrons takes place. The cations basically move to the cathode and anions move at the anode.