Here's why:

* Acids donate protons (H+) when dissolved in water.

* Bases accept protons (H+).

* Salts are formed by the reaction of an acid and a base.

When acetic acid reacts with a base, it loses a proton (H+) and becomes the acetate ion (CH3COO-). This acetate ion then combines with a cation (positive ion) from the base to form a salt.

For example, when acetic acid reacts with sodium hydroxide (NaOH), the following reaction occurs:

CH3COOH + NaOH → CH3COO-Na+ + H2O

The resulting salt is sodium acetate (CH3COO-Na+).