Chapter 9, Problem 9.49PP

a.

Summary Introduction

To determine:

The stronger acid from the given pair of acids ${\text{H}}_{\text{2}}{\text{PO}}_{\text{4}}{}^{-}$ and ${\text{HPO}}_{\text{4}}{}^{2-}$.

Introduction:

The ${\text{pK}}_{\text{a}}$ is defined as the negative base-10 logarithm of the acid dissociation constant $\left({\text{K}}_{\text{a}}\right)$ of a solution.

$\text{p}{K}_{\text{a}}=-{\log }_{10}{K}_{\text{a}}$

The strengths of acids are compared by their $\text{p}{K}_{\text{a}}$ values. The acid that has the lowest value of $\text{p}{K}_{\text{a}}$ among the given acid, has high acidic strength.

b.

Summary Introduction

To determine:

The stronger acid from the given pair of acids ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}$ and acetic acid.

Introduction:

The ${\text{pK}}_{\text{a}}$ is defined as the negative base-10 logarithm of the acid dissociation constant $\left({\text{K}}_{\text{a}}\right)$ of a solution.

$\text{p}{K}_{\text{a}}=-{\log }_{10}{K}_{\text{a}}$

The strengths of acids are compared by their $\text{p}{K}_{\text{a}}$ values. The acid that has the lowest value of $\text{p}{K}_{\text{a}}$ among the given acid, has high acidic strength.

c.

Summary Introduction

To determine:

The stronger acid from the given pair of acids formic acid and carbonic acid.

Introduction:

The ${\text{pK}}_{\text{a}}$ is defined as the negative base-10 logarithm of the acid dissociation constant $\left({\text{K}}_{\text{a}}\right)$ of a solution.

$\text{p}{K}_{\text{a}}=-{\log }_{10}{K}_{\text{a}}$

The strengths of acids are compared by their $\text{p}{K}_{\text{a}}$ values. The acid that has the lowest value of $\text{p}{K}_{\text{a}}$ among the given acid, has high acidic strength.

d.

Summary Introduction

To determine:

The stronger acid from the given pair of acids ammonium ion and hydrocyanic acid.

Introduction:

The ${\text{pK}}_{\text{a}}$ is defined as the negative base-10 logarithm of the acid dissociation constant $\left({\text{K}}_{\text{a}}\right)$ of a solution.

$\text{p}{K}_{\text{a}}=-{\log }_{10}{K}_{\text{a}}$

The strengths of acids are compared by their $\text{p}{K}_{\text{a}}$ values. The acid that has the lowest value of $\text{p}{K}_{\text{a}}$ among the given acid, has high acidic strength.