A buffer resists change in pH when a small amount of acid or base is added to it.
Explanation
- A buffer solution consists of a weak acid and its conjugate base or a weak base and its conjugate acid. It works by neutralizing the added acid (H+ ions) or base (OH- ions), thereby maintaining a relatively constant pH.
- The pH of a buffer does change slightly when acid or base is added, but the change is very small compared to non-buffered solutions. This small change is what is meant by "resistance" to pH change.
- The effectiveness or capacity of a buffer is defined by how much acid or base can be added before the pH changes significantly.
- Buffers can maintain pH within a range and absorb small amounts of strong acid or base without large pH shifts.
Therefore, the blank in the sentence can be filled with:
"a small" or "a limited" amount of acid or base. So the full statement is:
A buffer resists change in pH when a small amount of acid or base is added to
it. This is because it neutralizes that small amount through the equilibrium
between the weak acid/base and its conjugate, preventing large pH shifts.
