Benzoic acid is more soluble in alkaline solutions due to the formation of benzoate salts. When benzoic acid dissolves in an alkaline solution, it undergoes a chemical reaction with the hydroxide ions (OH-) present in the solution. This reaction results in the formation of benzoate ions (C6H5COO-) and water molecules. The benzoate ions are more soluble in water compared to benzoic acid, which leads to an increased solubility of benzoic acid in alkaline solutions.

The chemical equation for the reaction between benzoic acid and hydroxide ions is:

C6H5COOH + OH- → C6H5COO- + H2O

The benzoate ions formed in this reaction are resonance-stabilized, meaning that the negative charge is distributed over the entire molecule. This resonance stabilization makes the benzoate ions more polar and hence more soluble in water. In contrast, benzoic acid is a relatively nonpolar molecule, which makes it less soluble in water.

The extent of benzoic acid solubility in alkaline solutions depends on the concentration of hydroxide ions. As the concentration of hydroxide ions increases, the solubility of benzoic acid also increases. This is because a higher concentration of hydroxide ions means that there are more ions available to react with benzoic acid and form benzoate ions.

In summary, benzoic acid is more soluble in alkaline solutions due to the formation of benzoate salts. These salts are more soluble in water compared to benzoic acid, which leads to an increased solubility of benzoic acid in alkaline environments.