MCQEasyJEE 2023Carboxylic Acids

JEE Chemistry 2023 Question with Solution

The reaction used for preparation of soap from fat is:

  • A

    an addition reaction

  • B

    an oxidation reaction

  • C

    alkaline hydrolysis reaction

  • D

    reduction reaction

Answer

Correct answer:C

Step-by-step solution

Standard Method

Given: The reaction used for preparation of soap from fat is to be identified.

Find: The correct reaction type.

Soap is prepared from fats by saponification. The solution states that saponification is a type of alkaline hydrolysis reaction.

The general reaction is:

Ester (Triglyceride)+Base (NaOH)Alcohol (Glycerol)+Soap (Fatty Acid)\text{Ester (Triglyceride)} + \text{Base (NaOH)} \longrightarrow \text{Alcohol (Glycerol)} + \text{Soap (Fatty Acid)}

Triglycerides are esters, and in the presence of a strong base such as NaOH\text{NaOH}, their ester bonds undergo hydrolysis. This produces glycerol and the sodium salts of fatty acids, which are soaps.

Therefore, the reaction used for preparation of soap from fat is alkaline hydrolysis reaction.

The correct option is C.

Common mistakes

  • Confusing saponification with an addition reaction. This is incorrect because no reagent is being added across a multiple bond. Instead, ester bonds in fats are broken by base. Identify the functional group first: fat behaves as an ester undergoing hydrolysis.

  • Choosing oxidation because the process seems chemical and industrial. This is incorrect because the key transformation is cleavage of ester bonds by NaOH\text{NaOH}, not an increase in oxidation state. Focus on the reaction mechanism, not the context of soap manufacture.

  • Mistaking the reaction for reduction. This is incorrect because there is no gain of hydrogen or decrease in oxidation state driving the classification. The correct classification is base-mediated hydrolysis of an ester.

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