Chapter 2, Problem 7P

Interpretation Introduction

Interpretation:

The pH values for the titration of 500 mL of 0.010 M acetic acid with 0.010 M KOH should be calculated and the titration curve should be drawn.

Concept Introduction:

For a weak acid or a weak base, the dissociation reaction is in equilibrium and the equilibrium constant is known as acid or base dissociation constant. For such a solution, concentration of each species is calculated using ICE table.

The pH of solution is calculated as follows:

$\text{pH}=-\log \left[{\text{H}}^{+}\right]$

Here, $\left[{\text{H}}^{+}\right]$ is concentration of hydrogen ions in the solution.

For a buffer solution, pH is calculated using Henderson-Hasselbalch equation as follows:

$\text{pH}={\text{pK}}_{\text{a}}+\log \frac{\left[\text{Conjugate base}\right]}{\left[\text{acid}\right]}$

Here, pH is $-\log \left[{\text{H}}^{+}\right]$ of solution and ${\text{pK}}_{\text{a}}$ is $\text{-log}\left({\text{K}}_{\text{a}}\right)$ of weak acid.

Pictorial representation:

The titration curve for weak acid and strong base is as follows: