Strong and weak acids and bases

Strong Acids and Bases

Strong acids and bases completely ionise in solution, meaning they dissociate to release all of their hydrogen or hydroxide ions.
Common examples of strong acids include hydrochloric acid (HCl), nitric acid (HNO3) and sulfuric acid (H2SO4).
Examples of strong bases include sodium hydroxide (NaOH), potassium hydroxide (KOH) and lithium hydroxide (LiOH).
The pH of a strong acid is often lower than that of a weaker acid because it has more free H+ ions. Similarly, the pH of a strong base is often higher than that of a weaker one due to more free OH- ions.
Strong acids and bases are often corrosive and can pose potential hazards if not handled appropriately.
Note that the ‘strength’ of an acid or base doesn’t refer to its concentration. It’s determined by the extent to which it can ionise in solution.

Weak Acids and Bases

Weak acids and bases only partially ionise in solution, meaning only a fraction of the acid or base molecules donate or accept protons.
Acetic acid (found in vinegar) and ammonia are common examples of weak acids and bases respectively.
Weak acids and bases produce fewer ions in solution, so they have a higher pH (for weak acids) or lower pH (for weak bases) than their stronger equivalents.
These tend to be less corrosive than strong acids and bases. However, they can still present hazards, especially in high concentrations.
Buffer solutions often contain weak acids or bases. These are used to maintain a relatively constant pH, which can be crucial in many biological and chemical processes.

Comparing Strong and Weak Acids/Bases

By comparing the pH of different acids and bases, you can often predict whether they’re strong or weak.
Knowing if an acid or base is strong or weak helps to predict how they’ll react in different circumstances. For example, strong acids can react more violently with certain metals, compared to weak acids.
In titration experiments, knowing the strength of the acid or base helps determine the equivalence point (the point at which the reaction is complete), and thus the unknown concentration of the other reactant.
Both strong and weak acids/bases can be found in household, industrial and natural environments, emphasising the importance of understanding their properties and potential risks.