Chapter 6, Problem 6.35P

(a)

Interpretation Introduction

Interpretation:

Following reaction, conjugate acid-base pairs has to be identified.

Concept introduction:

Conjugate acid-base pair:

By gain or loss of ${\text{H}}^{\text{+}}$ conjugate acid-bases are related to each other.

Consider acid $\text{HA}$ with its corresponding base ${\text{A}}^{\text{-}}$ they are collectively known as conjugate acid-base pair since they are associated with gain or loss of proton.

Conjugate base of weak acid is a weak base.

Conjugate acid of weak base is a weak acid.

Answer to Problem 6.35P

For given reaction, acid –base pair is,

$\begin{array}{l}\begin{array}{cc}Acid& Base\\ {\text{ H}}_{\text{3}}{\text{O}}^{\text{+}}& {\text{ H}}_{\text{2}}\text{O}\end{array}\\ {\text{H}}_{\text{3}}{\text{N}}^{\text{+}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{N}}^{\text{+}}{\text{H}}_{\text{3}}{\text{H}}_{\text{3}}{\text{N}}^{\text{+}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{NH}}_2\end{array}$

Explanation of Solution

Given reaction is

$\begin{array}{l}{\text{H}}_{\text{3}}{\text{N}}^{\text{+}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{N}}^{\text{+}}{\text{H}}_{\text{3}}\text{+}{\text{H}}_{\text{2}}\text{O}\stackrel{}{\rightleftharpoons }{\text{H}}_{\text{3}}{\text{N}}^{\text{+}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}{\text{+H}}_{\text{3}}{\text{O}}^{\text{+}}\\ \text{Acid}\text{base}\text{conjugate base}\text{conjugate acid}\\ \end{array}$

By the concept of Bronsted-Lowry acid- base, the base which accept a proton called conjugated acid and similarly the acid which donates a proton called conjugate base.

Hence, the acid-base pair in this reaction is,

$\begin{array}{l}\begin{array}{cc}Acid& Base\\ {\text{ H}}_{\text{3}}{\text{O}}^{\text{+}}& {\text{ H}}_{\text{2}}\text{O}\end{array}\\ {\text{H}}_{\text{3}}{\text{N}}^{\text{+}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{N}}^{\text{+}}{\text{H}}_{\text{3}}{\text{H}}_{\text{3}}{\text{N}}^{\text{+}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{NH}}_2\end{array}$

(b)

Interpretation Introduction

Interpretation:

Following reaction, conjugate acid-base pairs has to be identified.

Concept introduction:

Conjugate acid-base pair:

By gain or loss of ${\text{H}}^{\text{+}}$ conjugate acid-bases are related to each other.

Consider acid $\text{HA}$ with its corresponding base ${\text{A}}^{\text{-}}$ they are collectively known as conjugate acid-base pair since they are associated with gain or loss of proton.

Conjugate base of weak acid is a weak base.

Conjugate acid of weak base is a weak acid.

Answer to Problem 6.35P

For given reaction, acid –base pair is,

$\begin{array}{l}\begin{array}{cc}Acid& Base\\ {\text{ C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CO}}_{\text{2}}\text{H}& {\text{ C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CO}}_2^{-}\end{array}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{NH}}^{\text{+}}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{N}\end{array}$

Explanation of Solution

Given reaction is

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CO}}_{\text{2}}\text{H+}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{N}\stackrel{}{\rightleftharpoons }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CO}}_{\text{2}}^{\text{-}}\text{+}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{NH}}^{\text{+}}\\ \text{Acid}\text{base}\text{conjugate base}\text{conjugate acid}\\ \end{array}$

By the concept of Bronsted-Lowry acid- base, the base which accept a proton called conjugated acid and similarly the acid which donates a proton called conjugate base.

Hence, the acid-base pair in this reaction is,

$\begin{array}{l}\begin{array}{cc}Acid& Base\\ {\text{ C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CO}}_{\text{2}}\text{H}& {\text{ C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CO}}_2^{-}\end{array}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{NH}}^{\text{+}}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{N}\end{array}$