Buffer solution

• A buffer solution resists significant changes in pH when small amounts of acid or base are added or when diluted.
• Buffers are crucial in biological systems, industrial processes, and analytical chemistry.

Types of Buffer Solutions:

Acidic Buffer:

• Contains a weak acid and its conjugate base (e.g., acetic acid and sodium acetate).
• The weak acid neutralizes added base, and the conjugate base neutralizes added acid.

Basic Buffer:

• Contains a weak base and its conjugate acid (e.g., ammonia and ammonium chloride).
• The weak base neutralizes added acid, and the conjugate acid neutralizes added base.

Properties of Buffer Solution:

pH Stability:

• Buffers resist pH changes due to the presence of both a weak acid and its conjugate base (or weak base and its conjugate acid).

Optimal Buffering Range:

• Buffers are most effective within one pH unit of the pKa (or pKb for bases) of the weak acid or base used.

Limited Buffering Capacity:

• Buffers have a finite capacity. Once depleted, the buffer’s pH changes more significantly upon further addition of acid or base.

Buffer Equations:

1) Henderson-Hasselbalch Equation (for acidic buffers):

$pH=pKa+log⁡([A^- ]/[HA] )$

2) For basic buffers (in terms of pOH):

$pOH=pKb+log⁡([B]/[HB^+ ] )$

Then, use pH + pOH = 14 (at 25°C) to find the pH.

Buffer Capacity:

• A measure of a buffer’s ability to resist pH changes upon adding acid or base.
• Maximum buffer capacity occurs when the concentrations of the weak acid/base and their conjugates are equal (pH = pKa or pOH = pKb).
• Higher buffer component concentrations result in greater capacity to neutralize added acids or bases

$β=dC/dpH$

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