Chapter 18.3, Problem 43SSC

Interpretation Introduction

Interpretation:

The effect on a neutral solution when it becomes acidic or basic is to be explained.

Concept introduction:

A solution is neutral if hydrogen ion and hydroxyl ion concentration in the solution is equal.

A solution is acidic if hydrogen ion is more than hydroxyl ion concentration in the solution.

A solution is basic if hydrogen ion is less than hydroxyl ion concentration in the solution.

Answer to Problem 43SSC

When the solution becomes acidic, its $\text{p}\text{H}\text{s}\text{h}\text{i}\text{f}\text{t}\text{s}\text{f}\text{r}\text{o}\text{m}7-0$ . Hydrogen ion concentration increases and hydroxyl ion concentration decreases.

When the solution becomes basic, its $\text{p}\text{H}\text{s}\text{h}\text{i}\text{f}\text{t}\text{s}\text{f}\text{r}\text{o}\text{m}7-14$ . Hydrogen ion concentration decreases and hydroxyl ion concentration increases.

Explanation of Solution

  $\begin{array}{l}\text{p}\text{H}\text{v}\text{a}\text{l}\text{u}\text{e}\text{o}\text{f}\text{a}\text{c}\text{i}\text{d}\text{i}\text{s}\text{i}\text{n}\text{r}\text{a}\text{n}\text{g}\text{e}1-7\end{array}$

  $\begin{array}{c}\text{p}\text{H}\text{v}\text{a}\text{l}\text{u}\text{e}\text{o}\text{f}\text{b}\text{a}\text{s}\text{e}\text{i}\text{s}\text{i}\text{n}\text{r}\text{a}\text{n}\text{g}\text{e}7-14\end{array}$

  $\begin{array}{c}\text{N}\text{e}\text{u}\text{t}\text{r}\text{a}\text{l}\text{s}\text{o}\text{l}\text{u}\text{t}\text{i}\text{o}\text{n}\text{h}\text{a}\text{s}\text{p}\text{H}=7\end{array}$

  $\text{p}\text{H}+\text{p}\text{O}\text{H}=14$

As $\text{p}\text{H}$ increases, hydrogen ion concentration decreases and hydroxyl ion concentration increases.

  $\begin{array}{l}\text{p}\text{O}\text{H}\text{v}\text{a}\text{l}\text{u}\text{e}\text{o}\text{f}\text{a}\text{c}\text{i}\text{d}\text{i}\text{s}\text{i}\text{n}\text{r}\text{a}\text{n}\text{g}\text{e}7-14\end{array}$

  $\begin{array}{c}\text{p}\text{O}\text{H}\text{v}\text{a}\text{l}\text{u}\text{e}\text{o}\text{f}\text{b}\text{a}\text{s}\text{e}\text{i}\text{s}\text{i}\text{n}\text{r}\text{a}\text{n}\text{g}\text{e}1-7\end{array}$

  $\begin{array}{c}\text{N}\text{e}\text{u}\text{t}\text{r}\text{a}\text{l}\text{s}\text{o}\text{l}\text{u}\text{t}\text{i}\text{o}\text{n}\text{h}\text{a}\text{s}\text{p}\text{O}\text{H}=7\end{array}$

As $\text{p}\text{O}\text{H}$ increases, hydrogen ion concentration increases and hydroxyl ion concentration decreases.

Conclusion

In nutshell,

  $\text{I}\text{f}\left[{\text{H}}^{+}\right]=\left[\text{O}{\text{H}}^{-}\right]$, the solution is neutral.

  $\text{I}\text{f}\left[{\text{H}}^{+}\right]<\left[\text{O}{\text{H}}^{-}\right]$, the solution is basic.

  $\text{I}\text{f}\left[{\text{H}}^{+}\right]>\left[\text{O}{\text{H}}^{-}\right]$, the solution is acidic.