Question

A mixture of camphor and benzoic acid can be easily separated by

• A. fractional distillation
• B. sublimation
• C. extraction with a solvent
• D. chemical method

Answer 1

The correct option is D

chemical method

Explanation for the correct option

(D) Chemical method

• Benzoic acid is an acid and therefore reacts with a base but camphor is an organic compound that does not react with the base.
• Aqueous solution of sodium bicarbonate$\left({\mathrm{NaHCO}}_3\right)$ is used to separate the mixture of benzoic acid and camphor.
• Benzoic acid reacts with an aqueous solution of sodium bicarbonate to form sodium benzoate $\left({\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COONa}\right)$ which is water-soluble whereas camphor does not react with sodium bicarbonate.

Explanation for incorrect options

(A) Fractional distillation:-

• Fractional distillation is a method that is used to separate a mixture into its components by heating the mixture
• It is generally used when the boiling points of components have a difference of less than ${25}^{o}C$
• Camphor has a boiling point of ${209}^{o}C$ whereas benzoic acid has a boiling point of $249.2^{o}C$, therefore fractional distillation cannot be used to separate this mixture.

(B) Sublimation:-

• A process in which a substance gets converted directly from a solid state to a gaseous state is called sublimation.
• Both camphor and benzoic acid undergo sublimation therefore they cannot be separated by sublimation.

(C) Extraction with a solvent:-

• Solvent extraction is a method that is used to separate components of a mixture based on their solubility in two different immiscible liquids.
• For eg:- Solvent extraction is used when one component of the mixture is soluble in organic solvent and the other component is soluble in water.
• Both camphor and benzoic acid are soluble in organic solvents therefore the mixture cannot be separated using solvent extraction.

Therefore, the correct option is (d) the chemical method