Chapter 9, Problem 47P

Interpretation Introduction

(a)

Interpretation:

The strong acid from A and B if A dissociates to a greater extent in water needs to be determined.

Concept Introduction:

The Bronsted-Lowry acid-base theory was purposed by Bronsted and Lowery is called Bronsted-Lowry acid-base theory. It states that acid can give ${\text{H}}^{\text{+}}$ ions whereas a base can accept the ${\text{H}}^{\text{+}}$ ion in its solution. Hence, this theory is entirely based on the presence of ${\text{H}}^{\text{+}}$ ion in the given substance. It purposed the concept of conjugated acid-base pair. A Bronsted acid gives ${\text{H}}^{\text{+}}$ ion to form conjugated base whereas a Bronsted base accepts ${\text{H}}^{\text{+}}$ ion to form its conjugated acid.

  $\begin{array}{l}{\text{ HA + H}}_{\text{2}}\text{O }\underset{}{\to }{\text{ A}}^{\text{-}}{\text{ + H}}_{\text{3}}{\text{O}}^{\text{+}}\\ \text{Bronsted + Bronsted Conjugated Conjugated}\\ \text{ Acid base base acid}\end{array}$

A strong acid shows complete dissociation to respective anion and ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ whereas, a weak acid can only partially ionize to its respective ions.

The strength of acid can be determined with the help of acid dissociation constant also. For acid HA the acid dissociation constant in its aqueous solution can be written as:

  $\text{HA }\underset{}{\rightleftarrows }{\text{A}}^{-}+{\text{H}}^{\text{+}}$

Here the equilibrium constant is called as acid dissociation constant. It is denoted as ${\text{K}}_{\text{a}}$ . It represents the ratio of equilibrium concentration of product and reactant molecule. For the given acid dissociation, the ${\text{K}}_{\text{a}}$ expression can be written as:

  ${\text{K}}_{\text{a}}\text{ = }\frac{{\text{[H}}^{\text{+}}{\text{][A}}^{\text{-}}\text{]}}{\text{[HA]}}$

Interpretation Introduction

(b)

Interpretation:

The strong acid from A and B, if A has smaller value of ${\text{K}}_{\text{a}}$ needs to be determined.

Concept Introduction:

The Bronsted-Lowry acid-base theory was purposed by Bronsted and Lowery is called Bronsted-Lowry acid-base theory. It states that acid can give ${\text{H}}^{\text{+}}$ ions whereas a base can accept the ${\text{H}}^{\text{+}}$ ion in its solution. Hence, this theory is entirely based on the presence of ${\text{H}}^{\text{+}}$ ion in the given substance. It purposed the concept of conjugated acid-base pair. A Bronsted acid gives ${\text{H}}^{\text{+}}$ ion to form conjugated base whereas a Bronsted base accepts ${\text{H}}^{\text{+}}$ ion to form its conjugated acid.

  $\begin{array}{l}{\text{ HA + H}}_{\text{2}}\text{O }\underset{}{\to }{\text{ A}}^{\text{-}}{\text{ + H}}_{\text{3}}{\text{O}}^{\text{+}}\\ \text{Bronsted + Bronsted Conjugated Conjugated}\\ \text{ Acid base base acid}\end{array}$

A strong acid shows complete dissociation to respective anion and ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ whereas a weak acid can only partially ionize to its respective ions.

The strength of acid can be determined with the help of acid dissociation constant also. For acid HA the acid dissociation constant in its aqueous solution can be written as:

  $\text{HA }\underset{}{\rightleftarrows }{\text{A}}^{-}+{\text{H}}^{\text{+}}$

Here, the equilibrium constant is called as acid dissociation constant. It is denoted as ${\text{K}}_{\text{a}}$ . It represents the ratio of equilibrium concentration of product and reactant molecule. For the given acid dissociation, the ${\text{K}}_{\text{a}}$ expression can be written as:

  ${\text{K}}_{\text{a}}\text{ = }\frac{{\text{[H}}^{\text{+}}{\text{][A}}^{\text{-}}\text{]}}{\text{[HA]}}$

Interpretation Introduction

(c)

Interpretation:

The strong acid from A and B, if the conjugated base of A is stronger than conjugated base of B needs to be determined.

Concept Introduction:

The Bronsted-Lowry acid-base theory was purposed by Bronsted and Lowery is called Bronsted-Lowry acid-base theory. It states that acid can give ${\text{H}}^{\text{+}}$ ions whereas a base can accept the ${\text{H}}^{\text{+}}$ ion in its solution. Hence, this theory is entirely based on the presence of ${\text{H}}^{\text{+}}$ ion in the given substance. It purposed the concept of conjugated acid-base pair. A Bronsted acid gives ${\text{H}}^{\text{+}}$ ion to form conjugated base whereas a Bronsted base accepts ${\text{H}}^{\text{+}}$ ion to form its conjugated acid.

  $\begin{array}{l}{\text{ HA + H}}_{\text{2}}\text{O }\underset{}{\to }{\text{ A}}^{\text{-}}{\text{ + H}}_{\text{3}}{\text{O}}^{\text{+}}\\ \text{Bronsted + Bronsted Conjugated Conjugated}\\ \text{ Acid base base acid}\end{array}$

A strong acid shows complete dissociation to respective anion and ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ whereas a weak acid can only partially ionize to its respective ions.

A strong acid forms a weak conjugated base whereas, a weak acid forms a strong conjugated base.