What are strong and weak acids?

Strong Acid

Weak Acid

An acid that completely dissociates in solution

An acid that only partially dissociates in solution

HA + H₂O → H₃O⁺ + A^-

HA + H₂O ⇋ H₃O⁺ + A^-

Large Ka value
Low pK_a

Small Ka value
High pK_a

An example is Hydrochloric acid (HCl): In solution, it almost entirely dissociates and exists as H+ ions and Cl^- ions

An example is acetic acid: In solution, only 50% dissociates into ions with the other 50% remaining as CH₃COOH