Chapter 15, Problem 15.112QE

(a)

Interpretation Introduction

Interpretation:

Solution of $0.25M{\text{ NH}}_{\text{4}}\text{Cl}$ has to be classified as either strongly acidic, weakly acidic, neutral, weakly basic, and strongly basic.

Concept Introduction:

The ionization of a hypothetical weak acid $\left(\text{HA}\right)$ is given as follows:

  $\text{HA}\left(\text{aq}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)\rightleftharpoons {\text{A}}^{-}\left(\text{aq}\right)+{\text{H}}_3{\text{O}}^{+}\left(\text{aq}\right)$

(b)

Interpretation Introduction

Interpretation:

The solution of $0.25M{\text{ Na}}_3{\text{PO}}_{\text{4}}$ has to be classified as either strongly acidic, weakly acidic, neutral, weakly basic, and strongly basic.

Concept Introduction:

Refer to part (a).

(c)

Interpretation Introduction

Interpretation:

The solution of $0.08M\text{ HI}$ has to be classified as either strongly acidic, weakly acidic, neutral, weakly basic, and strongly basic.

Concept Introduction:

The ionization of a hypothetical weak base is given as follows:

  $\text{B}\left(\text{aq}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)\rightleftharpoons {\text{BH}}^{\text{+}}\left(\text{aq}\right)+{\text{OH}}^{-}\left(\text{aq}\right)$

The expression of ${\text{K}}_{\text{b}}$ is given as follows:

  $K_{\text{b}}=\frac{\left[{\text{BH}}^{+}\right]\left[{\text{OH}}^{-}\right]}{\left[\text{B}\right]}$

Here,

$\left[\text{B}\right]$ denotes the concentration of hypothetical weak base.

$\left[{\text{OH}}^{-}\right]$ denotes the concentration of ${\text{OH}}^{-}$ ions.

$\left[{\text{BH}}^{+}\right]$ denotes the concentration of ${\text{BH}}^{+}$ ions.

$K_{\text{b}}$ denotes ionization constant of weak base.

(d)

Interpretation Introduction

Interpretation:

Solution of $0.12M\text{ LiI}$ has to be classified as either strongly acidic, weakly acidic, neutral, weakly basic, and strongly basic.

Concept Introduction:

Salts formed from alkali metal cation and halogens as anions are neutral. This is because the cation acts as spectator ion while the anion is not strong enough to react with water as halides are conjugate bases of strong hydrohalic acids.