What is the primary characteristic of a strong acid compared to a weak acid?

The primary characteristic of a strong acid is its ability to completely disassociate in water, releasing a high concentration of hydrogen ions (H⁺). This complete ionization results in a more significant effect on the pH level of the solution, making strong acids very effective in proton donation compared to weak acids, which only partially disassociate.

For example, when hydrochloric acid (a strong acid) is dissolved in water, it releases all of its hydrogen chloride molecules as H⁺ ions. In contrast, a weak acid like acetic acid will only partially dissociate, leading to fewer free hydrogen ions in solution. This complete disassociation is what allows strong acids to exhibit the characteristic low pH values when compared to weak acids at comparable concentrations.