pH is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm of the hydrogen ion concentration in moles per liter. The pH scale ranges from 0 to 14, with 0 being the most acidic and 14 being the most basic.

Strong acids are those that completely dissociate in water, releasing all of their hydrogen ions. This results in a high hydrogen ion concentration and a low pH. Weak acids, on the other hand, only partially dissociate in water, releasing only a small fraction of their hydrogen ions. This results in a lower hydrogen ion concentration and a higher pH.

For example, hydrochloric acid (HCl) is a strong acid that completely dissociates in water, releasing all of its hydrogen ions. This results in a pH of 0. Acetic acid (CH3COOH) is a weak acid that only partially dissociates in water, releasing only a small fraction of its hydrogen ions. This results in a pH of 4.8.