Engineering Chemistry Multiple Choice Questions on “Soaps”.
1. Soaps are _____________ based soapy detergents.
a) Water
b) Kerosene
c) Oil
d) Acid
Answer: c
Clarification: Soaps are oil based soapy detergents. Soaps for cleansing are obtained by treating vegetable or animal oils and fats with a strongly alkaline solution.
2. The saponification of a fat or oil is done using _______________ solution for hot process.
a) KOH
b) NaOH
c) HCl
d) NaCl
Answer: b
Clarification: The saponification of a fat or oil is done using NaOH solution for hot process. Saponification to the sodium salt of myristic acid takes place with NaOH in water. NaOH gives hard soaps.
3. The saponification of a fat or oil is done using _______________ solution for cold process.
a) KOH
b) NaOH
c) HCl
d) NaCl
Answer: a
Clarification: The saponification of a fat or oil is done using KOH solution for cold process. When potassium hydroxide (KOH) is used, a soft soap is formed. It cannot be used in hard water.
4. Soft soaps are the limitation of hot process because of their ____________
a) High alkalinity
b) Low alkalinity
c) Low solubility in water
d) High solubility in water
Answer: d
Clarification: Soft soaps are the limitation of the hot process because of their greater solubility in water. When potassium hydroxide (KOH) is used, a soft soap is formed by the cold process. It cannot be used in hard water.
5. Select the incorrect statement from the following option.
a) Hard soaps are the sodium carboxylates
b) Soft soaps are potassium carboxylates
c) Hard soaps are manufactured by cold process
d) Example of soft soap – shampoo and shaving cream
Answer: c
Clarification: Hard soaps are manufactured by hot process and soft soaps are manufactured by cold process.
6. Which of the following is the residual product in the formation of soap?
a) Glyceraldehyde
b) Glycerol
c) Glycerine
d) Acrylonitrile
Answer: b
Clarification: Glycerol is the residual product in the formation of soap. The immediate product is called an orthoester:
7. Which of the following is a typical soap molecule?
a) Calcium stearate
b) Potassium permanganate
c) Sodium bicarbonate
d) Sodium stearate
Answer: d
Clarification: Sodium stearate is a typical soap molecule. Sodium stearate is the sodium salt of stearic acid. Sodium stearate has both hydrophilic and hydrophobic parts, the carboxylate and the long hydrocarbon chain, respectively.
8. Select the correct statement from the following options.
a) The soap micelle is unstable due to positive charge on its head
b) The soap micelle is stable due to positive charge on its head
c) The soap micelle is unstable due to negative charge on its head
d) The soap micelle is stable due to negative charge on its head
Answer: d
Clarification: The soap micelle is stable due to the negative charge on its polar head. It carries a negative charge due to attractive forces.
9. Soaps do not act efficiently in hard water and in acidic solution.
a) True
b) False
Answer: a
Clarification: Soaps do not act efficiently in hard water and in acidic solution due to their softness as compared to detergents. Soaps are the soft detergents and cannot be used in water containing calcium and magnesium salts.