Chapter 2, Problem 72P

(a)

Interpretation Introduction

Interpretation: The reason why the first $p{K}_a$ value is lower than $p{K}_a$ of acetic acid is to be determined. The reason why the third $p{K}_a$ value is greater than $p{K}_a$ of acetic acid is to be determined.

Concept introduction:

Mixture of acid and base undergoes equilibrium reaction and it’s ${\text{pk}}_{\text{a}}$-values determine their direction of reaction.

Weak acids are more stable and less reactive, so equilibrium follows the direction of formation weak acids in a reaction.

Lesser the ${\text{pk}}_{\text{a}}$- value of compound will be more acidic. So the equilibrium follows the direction of compounds having low ${\text{pk}}_{\text{a}}$-value to the products of high ${\text{pk}}_{\text{a}}$ value.

Electronegativity: The chemical behavior of an atom where it attracts the shared electron pair to itself.

If hydrogen atoms in a compound are replaced by electronegative atoms, it causes inductive electron withdrawal. It stabilizes its conjugate base thus increases the strength of the acid.

(b)

Interpretation Introduction

Interpretation: The reason why the first $p{K}_a$ value is lower than $p{K}_a$ of acetic acid is to be determined. The reason why the third $p{K}_a$ value is greater than $p{K}_a$ of acetic acid is to be determined.

Concept introduction:

Mixture of acid and base undergoes equilibrium reaction and it’s ${\text{pk}}_{\text{a}}$-values determine their direction of reaction.

Weak acids are more stable and less reactive, so equilibrium follows the direction of formation weak acids in a reaction.

Lesser the ${\text{pk}}_{\text{a}}$- value of compound will be more acidic. So the equilibrium follows the direction of compounds having low ${\text{pk}}_{\text{a}}$-value to the products of high ${\text{pk}}_{\text{a}}$ value.