Question

Which of the following sets of materials can be used for conducting a saponification reaction for the preparation of soap.

• A. $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\mathrm{and}\mathrm{neem}\mathrm{oil}$
• B. $\mathrm{NaOH}\mathrm{and}\mathrm{neem}\mathrm{oil}$
• C. $\mathrm{NaOH}\mathrm{and}\mathrm{mineral}\mathrm{oil}$
• D. $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\mathrm{and}\mathrm{mineral}\mathrm{oil}$

Answer 1

The correct option is B

$\mathrm{NaOH}\mathrm{and}\mathrm{neem}\mathrm{oil}$

The explanation for the correct option:

B: $\mathrm{NaOH}\mathrm{and}\mathrm{neem}\mathrm{oil}$

• Soaps are formed by the Sodium and Potassium salts of long-chain acids.
• These acids when reacts either with Sodium hydroxide and Potassium hydroxide to form soap.
• This reaction is known as the saponification reaction.
• The esters react with alkali to form Ethanol and Sodium ethanoate.
• The chemical reaction occurs as follows:
  $\mathrm{C}\underset{(\mathrm{Ethyl}\mathrm{acetate})}{{\mathrm{H}}_3{\mathrm{COOC}}_2{\mathrm{H}}_5\left(\mathrm{l}\right)}+\underset{(\mathrm{Sodium}\mathrm{hydroxide})}{\mathrm{NaOH}\left(\mathrm{s}\right)}\to \underset{(\mathrm{Sodium}\mathrm{acetate})}{{\mathrm{CH}}_3\mathrm{COONa}\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Ethanol}\right)}{{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\left(\mathrm{l}\right)}$
• This implies that soap can be prepared by reacting Sodium hydroxide and neem oil.
• Instead of using mineral oil, neem oil can be used because mineral oil is more greasy and oily in nature.
• This greasy and oily nature will not be able to create lather(foam).

Hence the correct option is B.

The explanation for the incorrect option:

A: $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\mathrm{and}\mathrm{neem}\mathrm{oil}$

• Soap reacts with Calcium and Magnesium salts to form insoluble precipitates.
• These insoluble precipitates are known as scum.
• The Sulphates, bicarbonates, and Chlorides of Calcium and Magnesium make water hard in nature.
• The hard water does not make lather with such salts.
• This implies that $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\mathrm{and}\mathrm{neem}\mathrm{oil}$ cannot be used for conducting a saponification reaction for the preparation of soap.

Hence, the incorrect option is A.

C: $\mathrm{NaOH}\mathrm{and}\mathrm{mineral}\mathrm{oil}$

• Soaps are formed by reacting esters with alkali to form Ethanol and Sodium ethanoate.
• Soap reacts with Sodium and Potassium salts to form lather as they completely dissolve to form a neutral solution.
• Mineral oil is oily and greasy in nature and therefore the lather formation does not occur.
• This implies that $\mathrm{NaOH}\mathrm{and}\mathrm{mineral}\mathrm{oil}$ cannot be used for conducting a saponification reaction for the preparation of soap.

Hence, the incorrect option is C.

D: $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\mathrm{and}\mathrm{mineral}\mathrm{oil}$

• Soaps are formed by the Sodium and Potassium salts to form long-chain acids.
• When it reacts with calcium and Magnesium salts they make water hard in nature and hence no lather will be formed.
• Both $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\mathrm{and}\mathrm{mineral}\mathrm{oil}$ cannot be used for conducting a saponification reaction for the preparation of soap.
• Mineral oil is oily and greasy in nature and won't be able to make lather.

Hence, the incorrect option is D.

Therefore, option B is correct. $\mathrm{NaOH}\mathrm{and}\mathrm{neem}\mathrm{oil}$ can be used for conducting a saponification reaction for the preparation of soap.