Chapter 17, Problem 17.138QP

(a)

Interpretation Introduction

Interpretation:

The ionization of histidine, dipolar ion, isoelectric point and conjugate acid-base pair responsible for maintaining pH of blood has to be identified.

Concept introduction:

• ${\text{pK}}_{\text{a}}$ is defined as negative logarithm of acid dissociation constant( ${\text{K}}_{\text{a}}$).  ${\text{pK}}_{\text{a}}\text{=}{\text{-log}}_{\text{10}}{\text{(K}}_{\text{a}}\text{)}$
• The ${\text{pK}}_{\text{a}}$ is inversely proportional to acidity that is larger the value of ${\text{pK}}_{\text{a}}$ smaller the dissociation (weak acid) and smaller the value of ${\text{pK}}_{\text{a}}$ larger the dissociation (strong acid).
• The $\text{pH}$ at which certain molecule does not carry net electrical charge is called isoelectric point
• Dipolar ion is an ion having both positive and negative charge in it.

To give: The ionization of histidine in solution.

(b)

Interpretation Introduction

Interpretation:

The ionization of histidine, dipolar ion, isoelectric point and conjugate acid-base pair responsible for maintaining pH of blood has to be identified.

Concept introduction:

• ${\text{pK}}_{\text{a}}$ is defined as negative logarithm of acid dissociation constant( ${\text{K}}_{\text{a}}$).  ${\text{pK}}_{\text{a}}\text{=}{\text{-log}}_{\text{10}}{\text{(K}}_{\text{a}}\text{)}$
• The ${\text{pK}}_{\text{a}}$ is inversely proportional to acidity that is larger the value of ${\text{pK}}_{\text{a}}$ smaller the dissociation (weak acid) and smaller the value of ${\text{pK}}_{\text{a}}$ larger the dissociation (strong acid).
• The $\text{pH}$ at which certain molecule does not carry net electrical charge is called isoelectric point
• Dipolar ion is an ion having both positive and negative charge in it.

To identify: The dipolar ion from above ionization.

(c)

Interpretation Introduction

Interpretation:

The ionization of histidine, dipolar ion, isoelectric point and conjugate acid-base pair responsible for maintaining pH of blood has to be identified.

Concept introduction:

• ${\text{pK}}_{\text{a}}$ is defined as negative logarithm of acid dissociation constant( ${\text{K}}_{\text{a}}$).  ${\text{pK}}_{\text{a}}\text{=}{\text{-log}}_{\text{10}}{\text{(K}}_{\text{a}}\text{)}$
• The ${\text{pK}}_{\text{a}}$ is inversely proportional to acidity that is larger the value of ${\text{pK}}_{\text{a}}$ smaller the dissociation (weak acid) and smaller the value of ${\text{pK}}_{\text{a}}$ larger the dissociation (strong acid).
• The $\text{pH}$ at which certain molecule does not carry net electrical charge is called isoelectric point
• Dipolar ion is an ion having both positive and negative charge in it.

To calculate: The isoelectric point $\text{pI}$.

(d)

Interpretation Introduction

Interpretation:

The ionization of histidine, dipolar ion, isoelectric point and conjugate acid-base pair responsible for maintaining pH of blood has to be identified.

Concept introduction:

• ${\text{pK}}_{\text{a}}$ is defined as negative logarithm of acid dissociation constant( ${\text{K}}_{\text{a}}$).  ${\text{pK}}_{\text{a}}\text{=}{\text{-log}}_{\text{10}}{\text{(K}}_{\text{a}}\text{)}$
• The ${\text{pK}}_{\text{a}}$ is inversely proportional to acidity that is larger the value of ${\text{pK}}_{\text{a}}$ smaller the dissociation (weak acid) and smaller the value of ${\text{pK}}_{\text{a}}$ larger the dissociation (strong acid).
• The $\text{pH}$ at which certain molecule does not carry net electrical charge is called isoelectric point
• Dipolar ion is an ion having both positive and negative charge in it.

To identify: The conjugate acid-base pair responsible for maintaining pH of blood