Question

An acid is a substance that increases the concentration of H3O+ ions in solution. Look at the reaction below of phenol (C6H5OH) with water:

Upper C subscript 6 upper H subscript 5 upper o upper H (a q) plus upper H subscript 2 upper O (l) right arrow upper C subscript 6 upper H subscript 5 upper O superscript minus (a q) plus upper H subscript 3 upper O superscript plus (a q).

Which reactant acts as an acid by contributing a H+ ion to create H3O+ in the chemical equation?
C6H5OH(aq)
H2O(l)
C6H5O–(aq)
H3O+(aq)

Answer 1

C6H5OH(aq).

Phenol donates a proton (H+) to water, so by Bronsted–Lowry theory phenol is the acid and water is the base (forming H3O+).