Chemistry
Grade-7
Easy
Question
Which of the following is not used in the preparation of soap?
- Palmitic acid
- Stearic acid
- Acetic acid
- Lauric acid
Hint:
Also called ethanoic acid.
The correct answer is: Acetic acid
- Acetic acid is not used in the preparation of soap.
- Soaps are sodium or potassium salts of long-chain fatty acids.
- When triglycerides in fats/oils react with aqueous NaOH or KOH, they are converted to soaps and glycerol.
- This is called alkaline hydrolysis of the ester. Because this reaction leads to the formation of soap, it is called the saponification process.
- Lauric acid produces a foaming soap when saponified. This is an important property of soap. Therefore, it is common to use blends of oils to make soaps that lather but are neither too hard nor too soft.
- Stearic acid helps harden products such as candles and soap bars, the latter creating a rich lather with a velvety touch. This property makes it ideal for use in shaving creams. Due to its occlusive properties, it helps keep the skin hydrated by preventing or slowing the loss of water from the surface of the skin.
- The palmitic acid fraction of the oil, when saponified, gives soap some hardness, while oleic and linoleic acids provide softness.
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The correct option is d)Xe.
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