What is the difference between a strong acid and a weak acid?

The defining characteristic of a strong acid is its ability to completely dissociate into ions in an aqueous solution. This means that when a strong acid is mixed with water, it breaks apart fully, releasing all of its hydrogen ions (H+) into the solution. This complete dissociation leads to a higher concentration of hydrogen ions and, consequently, a lower pH (higher acidity).

In contrast, a weak acid does not fully dissociate; instead, it establishes an equilibrium between the undissociated acid and the dissociated ions. This results in a relatively lower concentration of hydrogen ions in solution compared to a strong acid, leading to a higher pH (lower acidity) than that of a strong acid at the same concentration.

Understanding this distinction is crucial for various applications in chemistry, including acid-base titrations and reactions that depend on pH levels. Strong acids can significantly influence pH because they provide a complete and immediate source of hydrogen ions, whereas weak acids contribute less drastically due to their partial dissociation.