Which species should be used to effectively separate a mixture of 2-chlorobenzoic acid and 4-Bromophenol?

To effectively separate a mixture of 2-chlorobenzoic acid and 4-bromophenol, sodium bicarbonate is the appropriate choice because it acts as a weak base that can deprotonate the carboxylic acid (2-chlorobenzoic acid), converting it into its corresponding salt, which is soluble in water. This transformation increases the polarity of 2-chlorobenzoic acid, allowing it to remain in the aqueous phase when the mixture is extracted with water.

On the other hand, 4-bromophenol, which is a phenolic compound, has a less acidic hydroxyl group and will not react significantly with sodium bicarbonate; it will remain largely in the organic phase during extraction. This selectivity allows for the separation of the two compounds based on their differing solubility characteristics after treatment with sodium bicarbonate.

Other options, such as water alone, would not provide a separation based on acidity and would not effectively differentiate the solubility of the two compounds. HCl could protonate the phenol, but would not facilitate the separation based on the solubility differences either. Sodium chloride, while it may help with solubility in some cases, does not possess the selective depro