Chapter 10, Problem 10.46AP

Interpretation Introduction

(a)

Interpretation:

The increasing order of acidity of the alcohols is to be stated.

Concept introduction:

Acidity of a molecule is dependent on the value of $\text{p}{K}_{\text{a}}$. This $\text{p}{K}_{\text{a}}$ value is known as the dissociation constant of an acid. The dissociation constant of an acid changes with the change in temperature. More is the value of $\text{p}{K}_{\text{a}}$, lesser is the acidity of an acid. Strength of an acid also depends upon the stability of the anion generated after loosing a hydrogen ion.

Answer to Problem 10.46AP

The increasing order of acidity of the alcohols is given below.

Explanation of Solution

Acidity of the molecules is dependent upon the stability of the ion formed after releasing hydrogen ion.

Sulfur atom present in $\text{1-}$ propanethiol is larger than the size of the oxygen atom. Therefore, negative charge present on sulfur atom is stabilized. Due to this $\text{1-}$ propanethiol is the strongest acid among the given molecules. Tertiary alcohols are more acidic than the secondary and primary alcohols. Therefore, $tert-\text{butyl}$ alcohol is the stronger acid than isopropyl alcohol and propyl alcohol.

Order of the acidity is shown below in Figure 1.

Figure 1

Conclusion

The increasing order of acidity of the molecules is $\text{propyl alcohol}<\text{isopropyl alcohol}<tert-\text{butyl alcohol}<\text{propanethiol}$.

Interpretation Introduction

(b)

Interpretation:

The increasing order of acidity of the molecules is to be stated.

Concept introduction:

Acidity of a molecule is dependent on the value of $\text{p}{K}_{\text{a}}$. This $\text{p}{K}_{\text{a}}$ value is known as the dissociation constant of an acid. The dissociation constant of an acid changes with the change in temperature. More is the value of $\text{p}{K}_{\text{a}}$, lesser is the acidity of an acid. Strength of an acid also depends upon the stability of the anion generated after loosing a hydrogen ion.

Answer to Problem 10.46AP

The increasing order of acidity of the molecules is given below.

Explanation of Solution

Acidity of the molecules is dependent upon the stability of the ion formed after releasing hydrogen ion. Sulfur atom present in $\text{3-}$ chloro $\text{-1-}$ propanethiol is larger than the size of the oxygen atom. Therefore, negative charge present on sulfur atom is stabilized. Due to this, $\text{3-}$ chloro $\text{-1-}$ propanethiol is the strongest acid among the given molecules. Position of the electronegative atom also determines the strength of an acid. Closer the electronegative atom to the negative charge generated after releasing the hydrogen ion, more is the strength of the acid.

Therefore, increasing order of the given molecules is shown below in Figure 2.

Figure 2

Conclusion

The increasing order of acidity of the given molecules is $\text{2-chloroethanol}<\text{3-chloro-1-propanethiol}<2\text{-chloro- 1-propanethiol}$.

Interpretation Introduction

(c)

Interpretation:

The increasing order of acidity of the molecules is to be stated.

Concept introduction:

Acidity of a molecule is dependent on the value of $\text{p}{K}_{\text{a}}$. This $\text{p}{K}_{\text{a}}$ value is known as the dissociation constant of an acid. The dissociation constant of an acid changes with the change in temperature. More is the value of $\text{p}{K}_{\text{a}}$, lesser is the acidity of an acid. Strength of an acid also depends upon the stability of the anion generated after loosing a hydrogen ion.

Answer to Problem 10.46AP

The increasing order of acidity of the molecules is stated below.

${\text{CH}}_{\text{3}}\text{N}\stackrel{}{¨}\text{H}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}\text{N}\stackrel{}{¨}\text{H}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\left({\text{CH}}_{\text{3}}\right)}_3\stackrel{+}{\text{N}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}$

Explanation of Solution

Acidity of the molecules is dependent upon the stability of the ion formed after releasing hydrogen ion. Nitrogen atom which is positively charged, stabilizes the negative charge which is generated after releasing the hydrogen ion. Therefore, structure 3 is the most stable structure with most acidic character. Position of the electronegative atom also determines the strength of an acid. Closer the electronegative atom to the generated negative charge after releasing the hydrogen ion, more is the strength of the acid.

Therefore, increasing order of the given molecules is stated below.

${\text{CH}}_{\text{3}}\text{N}\stackrel{}{¨}\text{H}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}\text{N}\stackrel{}{¨}\text{H}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\left({\text{CH}}_{\text{3}}\right)}_3\stackrel{+}{\text{N}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}$

Conclusion

The increasing order of acidity of the given molecules is ${\text{CH}}_{\text{3}}\text{N}\stackrel{}{¨}\text{H}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}\text{N}\stackrel{}{¨}\text{H}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\left({\text{CH}}_{\text{3}}\right)}_3\stackrel{+}{\text{N}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}$.

Interpretation Introduction

(d)

Interpretation:

The increasing order of acidity of the molecules is to be stated.

Concept introduction:

Acidity of a molecule is dependent on the value of $\text{p}{K}_{\text{a}}$. This $\text{p}{K}_{\text{a}}$ value is known as the dissociation constant of an acid. The dissociation constant of an acid changes with the change in temperature. More is the value of $\text{p}{K}_{\text{a}}$, lesser is the acidity of an acid. Strength of an acid also depends upon the stability of the anion generated after loosing a hydrogen ion.

Answer to Problem 10.46AP

The increasing order of acidity of the molecules is stated below.

$\begin{array}{l}{}^{-}\text{:}\underset{¨}{\ddot{\text{O}}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}\underset{¨}{\ddot{\text{O}}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}\\ <{\text{CH}}_{\text{3}}\underset{¨}{\ddot{\text{O}}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\stackrel{+}{\underset{¨}{\text{O}}}\text{H}\end{array}$

Explanation of Solution

Acidity of the molecules is dependent upon the stability of the ion formed after releasing the hydrogen ion. In structure $\text{4}$, a neutral species is generated after releasing the ${\text{H}}^{+}$ ion. Therefore, the molecule in structure $\text{4}$ is the most acidic in nature. Position of the electronegative atom also determines the strength of an acid. Closer the electronegative atom to the generated negative charge after releasing the hydrogen ion, more is the strength of an acid. Therefore, molecule $3$ is less acidic than molecule in structure $\text{4}$. In structure $1$, oxygen has already a negative charge. Therefore, it is already in its stabilized form and acts as a weakest acid among the given molecules.

Therefore, increasing order of acidity of the given molecules is stated below.

$\begin{array}{l}{}^{-}\text{:}\underset{¨}{\ddot{\text{O}}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}\underset{¨}{\ddot{\text{O}}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}\\ <{\text{CH}}_{\text{3}}\underset{¨}{\ddot{\text{O}}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\stackrel{+}{\underset{¨}{\text{O}}}\text{H}\end{array}$

Conclusion

The increasing order of acidity of the given molecules is ${}^{-}\text{:}\underset{¨}{\ddot{\text{O}}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}\underset{¨}{\ddot{\text{O}}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{O}\underset{¨}{\stackrel{}{¨}}\text{H}<{\text{CH}}_{\text{3}}\underset{¨}{\ddot{\text{O}}}-{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\stackrel{+}{\underset{¨}{\text{O}}}\text{H}$

Interpretation Introduction

(e)

Interpretation:

The increasing order of acidity of the molecules is to be stated.

Concept introduction:

Acidity of a molecule is dependent on the value of $\text{p}{K}_{\text{a}}$. This $\text{p}{K}_{\text{a}}$ value is known as the dissociation constant of an acid. The dissociation constant of an acid changes with the change in temperature. More is the value of $\text{p}{K}_{\text{a}}$, lesser is the acidity of an acid. Strength of an acid also depends upon the stability of the anion generated after loosing a hydrogen ion.

Answer to Problem 10.46AP

The increasing order of acidity of the molecules is stated below.

Explanation of Solution

Acidity of the molecules is dependent upon the stability of the ion formed after releasing the hydrogen ion. In structure $\text{3}$, Size of the sulfur atom is more as compared to the size of the oxygen atom. The ${\text{H}}^{+}$ ion is held loosely with the sulfur atom. Therefore, the molecule in structure $\text{3}$ easily releases the hydrogen ion and becomes the most acidic in nature. In structure $\text{2}$ and $\text{3}$, a neutral species is generated after releasing the ${\text{H}}^{+}$ ion Therefore, molecule $2$ and $\text{3}$ are more acidic than molecule $\text{1}$.

Therefore, increasing order of the given molecules is stated below in Figure 3.

Figure 3

Conclusion

The increasing order of acidity of the given molecules is shown above in Figure 3.