Engineering Chemistry Multiple Choice Questions on “Electroplating Baths – 2”.
1. Which of the following is used as an electrolyte for antimony Plating?
a) KNO3
b) Dilute H2SO4
c) Silver in potassium solution
d) HCl
Answer: c
Clarification: Usually in the antimony plating method, the pure antimony bar acts as the anode, the object is to be plated (impure metal) acts as the cathode and the silver in potassium solution acts as the electrolyte. When electricity is passed between the electrodes, the positive silver ions from the electrolyte move to the negative anode (the object), where they are neutralized by the electrons and adhere to the object as silver. On further transmission we get antimony deposition.
2. The electrolyte used in soft metal Plating is _____________
a) Sodium cyanide with caustic soda
b) Cyanide hexa Meta phosphate
c) Cyanide oxide
d) Cyanide peroxide
Answer: a
Clarification: Usually in the soft metal plating method, the pure metal bar acts as the anode, the object is to be plated (impure metal) acts as the cathode and the sodium cyanide along with caustic soda solution acts as the electrolyte. When electricity is passed between the electrodes, the positive metal ions from the electrolyte move to the negative anode (the object), where they are neutralized by the electrons and adhere to the object as soft metal.
3. Which of the following metals cannot be electro plated?
a) Tungsten
b) Nickel
c) Silver
d) Copper
Answer: a
Clarification: Since tungsten does not have discharge capacity, it cannot transfer electrons from one electrode to another easily which is why it can be electroplated. Tungsten is the least electroplated metal.
4. Which of the following is not a characteristic of electrolyte?
a) Enables transportation of electrons
b) Determines the strength of the metal
c) Determines solubility
d) Identifies discharge scale
Answer: c
Clarification: Since electrolyte is the main component in electroplating, it aids in flow of electrons from one electrode to another but it cannot identify the solubility of the material (it can only determine discharge capacity).
5. Identify the strong electrolyte from the following.
a) Caustic soda
b) Potassium chloride
c) Potassium sulphide
d) Barium chloride
Answer: b
Clarification: Since caustic soda dissociates completely in water, it gives equal proportions of hydrogen and hydroxide ions. That is why it is considered to be a strong solution. Where weak electrolytes are opposite of this.
6. Calculate the amount of electrolyte required for electroplating 50 grams of magnetite.
a) 60 ml
b) 70 ml
c) 80 ml
d) 100 ml
Answer: d
Clarification: We know that the amount of electrolyte required for electroplating metal is twice the amount of metal. Thus here since 50 grams of magnetite, the amount of electrolyte required is 50 x 2 = 100 ml.
7. Calculate the amount of metal used when 200 ml of NaCl?
a) 100 g
b) 0 g
c) 10 g
d) 5 g
Answer: a
Clarification: We know that the amount of electrolyte required for electroplating metal is twice the amount of metal. Thus here since 200 ml, the amount of metal required is 200/2=100 ml.
8. Which of the following can be used as an electrolyte for metal oxide deposition?
a) Sodium solution
b) NaCl solution
c) Water
d) Immiscible liquids
Answer: c
Clarification: Since for the deposition of metal oxide layer, charge carriers need to be absorbed by the materials and hence water can be used as an electrolyte to absorb charge carriers from metals.
9. Calculate the amount of water to be mixed (in ml) with the electrolyte from the give data.
Amount of metal oxide used: 100 g
Amount of electrolyte used: 10 ml
a) 10
b) 20
c) 30
d) 0
Answer: a
Clarification: We know that from Falton’s theory of electroplating, the amount of water used with metal is equal to metal oxide/electrolyte. So here it is 100/10=10.
10. Calculate the amount of water to be mixed (ml) with the electrolyte from the give data.
Amount of metal oxide used=12 g
Amount of electrolyte: 6 ml
a) 3
b) 2
c) 0
d) 1
Answer: b
Clarification: We know that from Falton’s theory of electroplating, the amount of water used with metal is equal to metal oxide/electrolyte. So here it is 12/6=2.