Chapter 19, Problem 19.112P

Interpretation Introduction

Interpretation:

A buffer is made by dissolving $0.80mol$ of $NaOH$ in $0.50L$ of $1.0M{H}_{3}P{O}_4$, the dissolving solution $pH$ has to be calculated.

Concept Introduction:

pH definition:

The pH of a solution is defined as the negative base-10 logarithm of the hydronium ion ${\text{[H}}_{\text{3}}{\text{O}}^{+}\text{]}$ concentration.

  $\text{pH}\text{=}{\text{-log[H}}_{\text{3}}{\text{O}}^{+}\text{]}$

Henderson-Hasselbalch equation:

The $\text{pH}$ at an intermediate stage of the titration is calculated by using the following equation,

  $\begin{array}{l}\text{pH}\text{=}{\text{pK}}_{\text{a}}\text{+}\text{log}{\frac{\left[\text{base}\right]}{\left[\text{acid}\right]}}_{}^{}\\ \text{where,}\\ \text{pH}\text{=}\text{-}\text{log}\left[{\text{H}}^{\text{+}}\right]\\ {\text{pK}}_{\text{a}}\text{=}\text{-}\text{log}{\text{K}}_{\text{a}}\\ \left({\text{K}}_{\text{a}}\text{-}\text{acid}\text{dissociation}\text{constant}\right)\end{array}$

This equation is known as Henderson-Hasselbalch equation.