What distinguishes a strong acid from a weak acid?

The key distinction between strong acids and weak acids lies in their behavior in aqueous solutions. Strong acids completely dissociate in water, meaning that they release all of their hydrogen ions (H⁺) into the solution. This complete dissociation results in a higher concentration of hydrogen ions, which leads to a lower pH and consequently a stronger acidity.

In contrast, weak acids do not fully dissociate; only a fraction of the acid molecules break apart to release hydrogen ions. This partial dissociation leads to a lower concentration of free hydrogen ions in solution and a higher pH compared to strong acids.

This fundamental difference is what qualifies an acid as strong or weak; it is not related to their boiling points, conductivity, or pH being inherently high or low across all conditions. Therefore, the complete dissociation characterizes strong acids as capable of producing more hydrogen ions in solution, making them distinctly stronger than their weak counterparts.