Why is phenol more acidic than ethanol ?

Explanation

(1) In ethanol, the `-OH` group is attached to `sp^(3)` hybridised carbon while in phenols, it is attached to `sp^(2)` hybridised carbon .
(2) Due to higher electro-negativity of `sp^(2)` hybridised carbon, electron density on oxygen decreases. This increases the polarity of `O-H` bond and result in more ionization of phenol than that of alcohols.

(3) In alkoxide ion, the negative charge is localized on oxygen, while in phenoxide ion the negative charge is delocalized. The delocalization of the negative charge (structures I to V) makes phenoxide ion more stable than that of phenol .

(4) The delocalization of charge in phenol (structures VI to X), the resonating structures have charge separaction (where oxygen atom of OH group to be positive and delocalization of negative charge over the ortho and para positions of aromatic ring) due to which phenol molecule is less stable than phenoxide ion. This favours ionization of phenol. Thus phenols are more acidic than ethanol.