(A) Phenols are more acidic than alcohols.
(R) Phenoxide ion is more stable than alkoxide ion due to resonance.

Phenols are more acidic than alcohols due to the difference in the stability of their corresponding conjugate bases. The conjugate base of phenol is the phenoxide ion, whereas the conjugate base of alcohol is the alkoxide ion. To understand this, let's explore why phenoxide ion is stable than phenol.

The Concept of Acidity

Acidity of a compound is determined by the ability of its conjugate base to stabilize the negative charge after deprotonation. A more stable conjugate base results in a stronger acid. In the case of phenol and alcohol, the conjugate base of phenol is the phenoxide ion, and the conjugate base of alcohol is the alkoxide ion.

Why Phenoxide Ion is More Stable Than Alkoxide Ion

The stability of the phenoxide ion can be attributed to the delocalization of the negative charge over the aromatic ring. This delocalization occurs due to resonance, which spreads the negative charge across several atoms, thereby stabilizing the phenoxide ion. In contrast, the alkoxide ion does not experience such resonance stabilization, as the negative charge is localized on the oxygen atom alone.

Therefore, why phenoxide ion is stable than phenol is explained by the resonance structure of the phenoxide ion, which stabilizes the negative charge effectively. This resonance effect is absent in alcohols, where the negative charge on the oxygen atom is not delocalized. As a result, the phenoxide ion is significantly more stable than the alkoxide ion, which makes phenol a stronger acid compared to alcohols.