What defines a strong acid?

A strong acid is characterized by its ability to completely dissociate into its ions when dissolved in water. This means that when a strong acid is placed in solution, all of its acid molecules break apart into hydrogen ions (H⁺) and their corresponding conjugate base ions. This full dissociation results in a high concentration of hydrogen ions in the solution, which is the defining feature of strong acids. This property not only influences the acid's strength but also its behavior in chemical reactions, particularly its ability to donate protons.

The concept of dissociation is critical here. Unlike weak acids, which only partially dissociate and maintain an equilibrium between the undissociated acid and its ions, strong acids go to completion. This is why strong acids are typically good at increasing the acidity of a solution and exhibiting strong electrophilic behavior when reacting with bases and other substances.