Chapter 17, Problem 31P

Interpretation Introduction

Interpretation:

The form/s of acetic acid present at pH 2.0 or lower, at 4.75 and at 8.0 higher.

Concept Introduction:

For an acid HA; the acid dissociation reaction can be written as.

$\text{HA}+{\text{H}}_{\text{2}}\text{O}\underset{}{\rightleftarrows }{\text{A}}^{-}+{\text{H}}_{\text{3}}{\text{O}}^{+}$

The acid dissociation constant (Ka) is the ratio of product and reactant for the acid dissociation reaction. Hence it can be written as;.

$K_{\text{a}}=\frac{\left[{\text{A}}^{-}\right]\left[{\text{H}}_{\text{3}}{\text{O}}^{+}\right]}{\left[\text{HA}\right]}$

Henderson-Hasselbalch equation purposed the relation between pH and pK_a for weak acids:

$\text{pH}=\text{p}{K}_{\text{a}}+\log \frac{\left[{\text{A}}^{-}\right]}{\left[\text{HA}\right]}$.