Engineering Chemistry Multiple Choice Questions on “Faraday’s Laws of Electrolysis”.
1. According to Faraday’s first law of electrolysis, the amount of any substance deposited at the electrode is directly proportional to the quantity of _______________
a) Voltage drop
b) Resistance
c) Electricity passed
d) Tolerance
Answer: c
Clarification: According to Faraday’s law of electrolysis, the amount of any substance deposited at the electrode is directly proportional to the quantity of electricity passed. It is given by:
m = (Q / F) * (M / Z)
where, m = Mass of the substance liberated at an electrode in grams
Q = Total electric charge passed through the substance in Coulombs
F = Faraday constant
M = Molar mass of the substance in grams per mol
Z = Valency number of ions of the substance
For Faraday’s first law, M, F, and z are constants, so that the larger the value of Q the larger m will be.
2. Electrochemical equivalent may be defined as the ____________ of the substance deposited by the passage of 1 coulomb of electricity.
a) Volume
b) Weight
c) Density
d) Velocity
Answer: b
Clarification: Electrochemical equivalent may be defined as the weight of the substance deposited by the passage of 1 coulomb of electricity. The electrochemical equivalent of an element is measured with a voltameter.
3. 1 Faraday = _______________
a) 1 coulomb
b) 1000 coulomb
c) 5000 coulomb
d) 96500 coulomb
Answer: d
Clarification: 1 Faraday = 96,500 Coulomb. It is calculated mathematically and is widely used everywhere.
4. According to Faraday’s second law, the weights of different substances evolved by the passage of the same quantity of electricity are proportional to their _______________
a) Chemical equivalent weight
b) Current supply
c) Chemical equivalent density
d) Volume
Answer: a
Clarification: According to Faraday’s second law, the weights of different substances evolved by the passage of same quantity of electricity are proportional to their chemical equivalent weights. For Faraday’s second law, Q, F, and z are constants, so that the larger the value of M/z (equivalent weight) the larger m will be.
5. Silver is electrodeposited on a metallic vessel of surface area 800 cm2 by passing a current of 0.2 A for 3 hours. The thickness of silver deposited is ____________
a) 0.1 mm
b) 0.02 mm
c) 0.05 mm
d) 0.2 mm
Answer: b
Clarification: The thickness of silver deposited is 0.0288 mm. It is calculated mathematically.
6. The velocity with which an ion moves under a potential gradient of __________ volt/cm in a solution is called ionic mobility.
a) 5
b) 4
c) 3
d) 1
Answer: d
Clarification: The velocity with which an ion moves under a potential gradient of one volt/cm in a solution is called ionic mobility. The separation of ions according to their mobility in the gas phase is called ion mobility spectrometry, in liquid phase, it is called electrophoresis.
7. The unit of ionic mobility in SI system is ____________
a) msV-1
b) m3sV2
c) m2s-1V-1
d) m2s-1V
Answer: c
Clarification: The unit of ionic mobility in SI system is m2s-1V-1. The separation of ions according to their mobility in gas phase is called ion mobility spectrometry, in liquid phase it is called electrophoresis.
8. Which of the following factor does not affect ionic mobility?
a) Pressure
b) Nature of ions
c) Temperature
d) Concentration of the solution