Chapter 16, Problem 16.118AP

(a)

Interpretation Introduction

Interpretation: The volume and mass of the unknown substance, the concentration of the base and change in $\text{pH}$ on addition of the given volumes of the base is given. The $K_{\text{a}}$ and the molar mass of the unknown acid is to be calculated.

Concept introduction: At half way from the beginning of the equivalence point, $\text{pH}$ is equal to $\text{p}{K}_{\text{a}}$.

At equivalence point,

${\left(\text{Molar}\text{concentration}\right)}_{\text{base}}\times {\left(\text{Volume}\right)}_{\text{base}}={\left(\text{Molar}\text{concentration}\right)}_{\text{acid}}\times {\left(\text{Volume}\right)}_{\text{acid}}$

To determine: The $K_{\text{a}}$ of the unknown acid.

(b)

Interpretation Introduction

To determine: The molar mass of the unknown acid.