Final answer:
A strong acid is an acid which is completely ionized in an aqueous solution. It means that all of the acid molecules dissociate into ions in water.
Step-by-step explanation:
A strong acid is an acid which is completely ionized in an aqueous solution. It means that all of the acid molecules dissociate into ions in water. For example, hydrogen chloride (HCl) is a strong acid because it ionizes completely into hydrogen ions (H+) and chloride ions (Cl-) in water:
HCl (g) → H+ (aq) + Cl- (aq)
On the other hand, a weak acid only ionizes slightly in an aqueous solution. Acetic acid (found in vinegar) is a common weak acid. Its ionization is shown below:
CH3COOH (aq) <==> CH3COO- (aq) + H+ (aq)