Chapter 16, Problem 16.122QP

(a)

Interpretation Introduction

Interpretation:

From the given equilibrium equations and ${\text{K}}_{\text{a}}$ value for the given three reaction systems,

The conjugate pair that would be best for preparing a buffer with a pH of 6.96 has to be given.

Concept Introduction:

Henderson-Hasselbalch equation:

The pH can be calculated using Henderson-Hasselbalch equation as follows,

$\begin{array}{l}\text{pH}{\text{= pK}}_{\text{a}}\text{ + log}\frac{[\text{conjugate base]}}{[\text{weak acid]}}\\ \text{pH}{\text{= pK}}_{\text{a}}\text{ + log}\frac{[{\text{A}}^{\text{-}}\text{]}}{[\text{HA]}}\end{array}$

Buffer:

A buffer is solution containing a mixture of two substances. A buffer solution is characterized by the tendency to resist changes in pH when some limited of amount of acid or base are added to it.

A buffer should possess either a weak acid and its conjugate anion that is a conjugate base (weak) or a weak base and its conjugate cation that is a conjugate acid (weak).

(b)

Interpretation Introduction

Interpretation:

From the given equilibrium equations and ${\text{K}}_{\text{a}}$ value for the given three reaction systems,

The preparation of 100 mL of a buffer with a pH of 6.96 by assuming to have a 0.10 M solutions of each pair has to be explained

Concept Introduction:

Henderson-Hasselbalch equation:

The pH can be calculated using Henderson-Hasselbalch equation as follows,

$\begin{array}{l}\text{pH}{\text{= pK}}_{\text{a}}\text{ + log}\frac{[\text{conjugate base]}}{[\text{weak acid]}}\\ \text{pH}{\text{= pK}}_{\text{a}}\text{ + log}\frac{[{\text{A}}^{\text{-}}\text{]}}{[\text{HA]}}\end{array}$

Buffer:

A buffer is solution containing a mixture of two substances. A buffer solution is characterized by the tendency to resist changes in pH when some limited of amount of acid or base are added to it.

A buffer should possess either a weak acid and its conjugate anion that is a conjugate base (weak) or a weak base and its conjugate cation that is a conjugate acid (weak).