Question

Why does benzoic acid not dissolve in water or HCl acid, but completely dissolves in NaOH?

Answer 1

First, the H₂O is one of the most polar solvents, this compound will dissolve components with a similar or same polarity of water.

In the case of benzoic acid, is a strong acid, but has a low solubility in water. However, it's conjugate base is more soluble than it acid. the conjugate base has a O^- that it can perfectly attract the ion, in this case, the Na from the NaOH, ocurring an acid base reaction. If forms H2O, Na+, benzene ring with an ester group that has a single bonded O- and a double bonded OH.

In HCl there are no reaction cause they are two acids, so no reaction is formed there.

Hope this helps