A Buffer Solution consists of a weak acid and its conjugate base. It maintains pH stability by neutralizing small amounts of added $H^+$ or $OH^-$.
$$\text{pH} = pK_a + \log_{10} \left( \frac{[\text{Base}]}{[\text{Acid}]} \right)$$
1. What is Buffer Capacity?
It is the amount of acid or base a buffer can neutralize before the pH changes significantly.
2. When is a buffer most effective?
Effectiveness peaks when $[Acid] = [Base]$, making $\text{pH} = pK_a$.
3. Can a buffer handle any amount of acid?
No. Once the conjugate base or acid is completely consumed, the buffer fails and the pH will spike or crash.