Chapter 14, Problem 14.38CP

(a)

Interpretation Introduction

Interpretation:

Given picture represents solutions of three salts $\text{NaA}$$\left({\text{A}}^{\text{-}}{\text{=X}}^{\text{-}}{\text{,Y}}^{\text{-}}{\text{and Z}}^{\text{-}}\right)$, three anions has to be arranged in order of increasing base strength.

Concept Introduction:

Bronsted-Lowry acid and bases:

The chemical species which is able to donate hydrogen ion to other substance known as B-L acid and the species which is able to accept hydrogen ion from another species known as B-L base.

Strong acid is $100\%$ ionized in an aqueous solution and strong base is $100\%$ protonated in an aqueous solution, so the concentration of ${\text{OH}}^{-}$ equal to the initial concentration.

(b)

Interpretation Introduction

Interpretation:

Given picture represent solutions of three salts $\text{NaA}$$\left({\text{A}}^{\text{-}}{\text{=X}}^{\text{-}}{\text{,Y}}^{\text{-}}{\text{and Z}}^{\text{-}}\right)$, anion which has strongest acid 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 strong acid is a weak base.

Conjugate acid of strong base is a weak acid.

(c)

Interpretation Introduction

Interpretation:

Given picture represent solution of three salts $\text{NaA}$$\left({\text{A}}^{\text{-}}{\text{=X}}^{\text{-}}{\text{,Y}}^{\text{-}}{\text{and Z}}^{\text{-}}\right)$, anion which has smallest ${\text{pK}}_{\text{b}}$ value has to be identified.

Concept Introduction:

Base dissociation constant $\left({\text{K}}_{\text{b}}\right)$:

It is an equilibrium constant which refers the dissociation (ionization) of base.

The value of ${\text{K}}_{\text{b}}$ can be calculated by using ${\text{K}}_{\text{a}}$ and vice versa.  This relation is given as,

${\text{K}}_{\text{a}}{\text{.K}}_{\text{b}}{\text{= K}}_{\text{w}}$

${\text{pK}}_{\text{b}}$ of the solution is the negative logarithm of base-10 of base dissociation constant.

${\text{pK}}_{\text{b}}\text{= -log}\left({\text{K}}_{\text{b}}\right)$

Relationship between $\text{pOH}$ and ${\text{pK}}_{\text{a}}$:

$\text{pOH=}\frac{\text{1}}{{\text{K}}_{\text{b}}}$

Solution has concentration of $\text{OH}$ high means the value of ${\text{K}}_{\text{b}}$ is low.

(d)

Interpretation Introduction

Interpretation:

Given picture represent solutions of three salts $\text{NaA}$$\left({\text{A}}^{\text{-}}{\text{=X}}^{\text{-}}{\text{,Y}}^{\text{-}}{\text{and Z}}^{\text{-}}\right)$, number of HA molecule and ${\text{OH}}^{\text{-}}$ anions are same within each salt solution.  This is has to be explained.

Concept Introduction:

Bronsted-Lowry acid and bases:

The chemical species which is able to donate hydrogen ion to other substance known as B-L acid and the species which is able to accept hydrogen ion from another species known as B-L base.

Strong acid is $100\%$ ionized in an aqueous solution and strong base is $100\%$ protonated in an aqueous solution, so the concentration of ${\text{OH}}^{-}$ equal to the initial concentration.