When acetic acid (CH3COOH) dissolves in water, it undergoes ionization or dissociation. During this process, the covalent bond between the hydrogen atom (H) and the oxygen atom (O) in the carboxyl group (-COOH) breaks, resulting in the release of a hydrogen ion (H+) and an acetate ion (CH3COO-).

The chemical equation for the dissociation of acetic acid can be represented as follows:

CH3COOH <=> H+ + CH3COO-

In this equilibrium reaction, the acetic acid molecule (CH3COOH) acts as the weak acid, donating a hydrogen ion (H+) to form a hydronium ion (H3O+) in solution. The acetate ion (CH3COO-) is the conjugate base of acetic acid.

The extent of dissociation of acetic acid in water is relatively low, meaning that only a small fraction of the acid molecules actually dissociate into ions. However, this dissociation is sufficient to give acetic acid its characteristic acidic properties, such as a sour taste and the ability to react with bases and release H+ ions.