Chapter 15, Problem 100AP

(a)

Interpretation Introduction

Interpretation : The concentration of ${\text{OH}}^{\text{-}}$ ions and the pH should be calculated if $\text{0}\text{.0200 M}$ solution of Novocain (a weak base) is taken in water with ${\text{K}}_{\text{b}}$ value as ${\text{7×10}}^{\text{-6}}\text{M}$ .

Concept Introduction : The pH of buffer solutions can be calculated with the help ofthe Henderson-Hasselbalch equation. The Henderson-Hasselbalch equation can be used that gives the relation between pH and ${\text{pK}}_{\text{a}}$ of weak acids. It is represented as follows:

$\begin{array}{l}\text{pH = pKa + log }\frac{\text{[Conjugated base]}}{\text{[Acid]}}\\ \\ \text{pOH = pKb + log }\frac{\text{[Salt]}}{\text{[base]}}\end{array}$

(b)

Interpretation Introduction

Interpretation : The pH at the equivalence point should be calculated if $\text{0}\text{.0200 M}$ solution of Novocain (a weak base) is titrated with 0.020 M HCl.

Concept Introduction: The pH of buffer solutions can be calculated with the help of the Henderson-Hasselbalch equation. The Henderson-Hasselbalch equation can be used that gives the relation between pH and ${\text{pK}}_{\text{a}}$ for weak acids. It is represented as follows:

$\begin{array}{l}\text{pH = pKa + log }\frac{\text{[Conjugated base]}}{\text{[Acid]}}\\ \\ \text{pOH = pKb + log }\frac{\text{[Salt]}}{\text{[base]}}\end{array}$