Acid-base buffers are essential solutions that maintain a relatively stable pH when small amounts of acids or bases are introduced. These buffers typically consist of a weak acid and its conjugate base, allowing them to neutralize added hydronium ions (H₃O⁺) or hydroxide ions (OH⁻). For instance, a buffer solution made from hydrofluoric acid (HF) and sodium fluoride (NaF) can effectively resist pH changes, maintaining a pH around 8.

When a strong acid, such as hydrobromic acid (HBr), is added to the buffer, the conjugate base (fluoride ion, F⁻) reacts with the hydronium ions produced by the strong acid. This reaction forms more hydrofluoric acid, thereby neutralizing the added acid. Although the pH of the solution may decrease slightly, for example to 7.8, the buffer's capacity prevents significant changes in pH.

Conversely, if a strong base is introduced, the weak acid component of the buffer (hydrofluoric acid) reacts with the hydroxide ions from the strong base. This neutralization produces water and releases more fluoride ions into the solution, which can slightly increase the pH, potentially to around 8.2. The buffer's design allows it to absorb these changes, ensuring that the pH remains relatively stable despite the addition of strong acids or bases, as long as the quantities added are not excessive.