Chapter 8, Problem 89P

Interpretation Introduction

(a)

Interpretation:

The equation for reaction when ${\text{H}}_{\text{3}}{\text{O}}^{+}$ is added to buffer solution containing equal amounts of HCOOH and ${\text{HCOO}}^{-}$ should be explained.

Concept Introduction:

On addition of limited amount of an acid or base, if a solution does not change the pH, it is known as buffer solution. For example: aqueous solution of weak acid and its conjugate base. This property of buffer to resist the pH is known as buffer action.

For an effective buffer, the value of pH is equal to the $\text{p}{K}_{\text{a}}$ of weak acid or at this condition, there is equal capacity in solution with respect to addition of an acid or a base. If pH value is less than the $\text{p}{K}_{\text{a}}$ value, the addition of base is favored by buffer capacity. Similarly, acid buffer capacity is more than the base buffer capacity if pH value is greater than the $\text{p}{K}_{\text{a}}$ value of weak acid. Depending on the concentration, more is the concentration of the weak acid and its conjugate base more will be the buffer capacity.

Interpretation Introduction

(b)

Interpretation:

The equation for reaction when ${\text{OH}}^{-}$ is added to buffer solution containing equal amounts of HCOOH and ${\text{HCOO}}^{-}$ should be explained.

Concept Introduction:

On addition of limited amount of an acid or base, if a solution does not change the pH, it is known as buffer solution. For example: aqueous solution of weak acid and its conjugate base. This property of buffer to resist the pH is known as buffer action.

For an effective buffer, the value of pH is equal to the $\text{p}{K}_{\text{a}}$ of weak acid or at this condition, there is equal capacity in solution with respect to addition of an acid or a base. If pH value is less than the $\text{p}{K}_{\text{a}}$ value, the addition of base is favored by buffer capacity. Similarly, acid buffer capacity is more than the base buffer capacity if pH value is greater than the $\text{p}{K}_{\text{a}}$ value of weak acid. Depending on the concentration, more is the concentration of the weak acid and its conjugate base more will be the buffer capacity.