Chapter 13.1, Problem 2P

(a)

Interpretation Introduction

Interpretation: The stronger acid of the given compounds has to be found.

Concept introduction:

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.  Electronegative of hybrid orbitals depends upon the % s character. Hence more the s character more the electronegativity.

The acidity depends upon the electronegativity of an atom. More the electronegativity more the acidity.

$\text{s}$ character decreases from $\text{sp}>{\text{sp}}^{\text{2}}>{\text{sp}}^{\text{3}}$. Therefore, acidity decreases from $\text{sp}>{\text{sp}}^{\text{2}}>{\text{sp}}^{\text{3}}$.

The oxygen is more electronegative. Therefore, it attracts a shared pair of electron pair of $\text{O}-\text{H}$ bond towards itself. As a result, $\text{O}-\text{H}$ bond is more easily broken.

(b)

Interpretation Introduction

Interpretation:

The greater ${\text{pK}}_{\text{a}}$ value of the given compounds has to be found.

Concept introduction:

The ionization constant ${\text{K}}_{\text{a}}$ of acids increases with increasing the strength of acid. The stronger the acid, higher the value of ionization constant ${\text{K}}_{\text{a}}$.

The relation between ${\text{K}}_{\text{a}}$ and ${\text{pK}}_{\text{a}}$ is expressed as,

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

The stronger the acid, lower the value of $\text{p}{K}_{\text{a}}$.