Chapter 16, Problem 50A

Interpretation Introduction

Interpretation:

The action of acid and base on various buffer combinations is to be discussed.

Concept introduction:

A solution is a buffer which resists the change in $\text{p}\text{H}$ value when a small amount of acid or base is added to it.

A buffer solution is of two types:

• Acidic buffer
• Basic buffer

The component necessary for buffer solution is

• Weak acid and a salt of a weak acid with a strong base.
• Weak base and a salt of a weak base with strong acid.

Answer to Problem 50A

$\text{H}\text{C}\text{N}-\text{N}\text{a}\text{C}\text{N}$:

$\begin{array}{l}\text{H}\text{C}\text{l}\to {\text{H}}^{+}(\text{p}\text{r}\text{o}\text{d}\text{u}\text{c}\text{e}\text{s}\text{c}\text{o}\text{m}\text{m}\text{o}\text{n}\text{i}\text{o}\text{n}\text{e}\text{f}\text{f}\text{e}\text{c}\text{t})+\text{C}{\text{l}}^{-}\\ {\text{H}}^{+}+\text{O}{\text{H}}^{-}(\text{f}\text{r}\text{o}\text{m}\text{b}\text{a}\text{s}\text{e})\to {\text{H}}_2\text{O}\end{array}$

$\text{H}\text{F}-\text{K}\text{F}$:

$\begin{array}{l}\text{H}\text{C}\text{l}\to {\text{H}}^{+}(\text{p}\text{r}\text{o}\text{d}\text{u}\text{c}\text{e}\text{s}\text{c}\text{o}\text{m}\text{m}\text{o}\text{n}\text{i}\text{o}\text{n}\text{e}\text{f}\text{f}\text{e}\text{c}\text{t})+\text{C}{\text{l}}^{-}\\ {\text{H}}^{+}+\text{O}{\text{H}}^{-}(\text{f}\text{r}\text{o}\text{m}\text{b}\text{a}\text{s}\text{e})\to {\text{H}}_2\text{O}\end{array}$

$\text{H}{\text{C}}_3{\text{H}}_5{\text{O}}_2-\text{N}\text{a}{\text{C}}_3{\text{H}}_5{\text{O}}_2$:

$\begin{array}{l}\text{H}\text{C}\text{l}\to {\text{H}}^{+}(\text{p}\text{r}\text{o}\text{d}\text{u}\text{c}\text{e}\text{s}\text{c}\text{o}\text{m}\text{m}\text{o}\text{n}\text{i}\text{o}\text{n}\text{e}\text{f}\text{f}\text{e}\text{c}\text{t})+\text{C}{\text{l}}^{-}\\ {\text{H}}^{+}+\text{O}{\text{H}}^{-}(\text{f}\text{r}\text{o}\text{m}\text{b}\text{a}\text{s}\text{e})\to {\text{H}}_2\text{O}\end{array}$

Explanation of Solution

The hydrogen ions produced by acid produce a common ion effect and the effect of increased hydrogen ions is neutralized.

The hydroxyl ions produced by the base react hydrogen ions of acid and neutralizes the effect of the base.

Thus, buffer resists change in $\text{p}\text{H}$ value of the solution.

Conclusion

Thus, the addition of acid and base in buffer solution gets neutralized if a small quantity of it is added.