The acidity of a compound is determined by its ability to donate a proton H+ and the stability of the resulting anion. Carboxylic acids RCOOH are more acidic than phenols ArOH due to the difference in the stability of their conjugate bases, which are carboxylate ions RCOO- and phenoxide ions ArO- , respectively.When a carboxylic acid donates a proton, it forms a carboxylate ion. The negative charge on the carboxylate ion is delocalized over two oxygen atoms through resonance, which stabilizes the ion. This delocalization of the negative charge reduces the electron density on each oxygen atom, making it less likely to attract the lost proton back. As a result, carboxylic acids are more willing to donate a proton and are thus more acidic.On the other hand, when a phenol donates a proton, it forms a phenoxide ion. In this case, the negative charge is delocalized over the entire aromatic ring through resonance. However, the delocalization is not as effective as in carboxylate ions because the negative charge is spread over a larger area, and the oxygen atom still retains a significant amount of electron density. This makes phenoxide ions less stable than carboxylate ions, and phenols are less willing to donate a proton, making them less acidic than carboxylic acids.In summary, the greater acidity of carboxylic acids compared to phenols is due to the increased stability of their conjugate bases carboxylate ions resulting from the effective delocalization of the negative charge over two oxygen atoms.