Chapter 18, Problem

Use the symbols $<,>,$ and = to express the relationship between the concentrations of ${\text{H}}^{+}$ ions and ${\text{OH}}^{-}$ ions in acidic, neutral, and basic solutions.

Interpretation Introduction

Interpretation:

The relationship between the concentrations of hydrogen ions and hydroxyl ions in acidic, basic and neutral solution is to be expressed.

Concept introduction:

According to Arrhenius,

Acid is a substance which gives hydrogen ion and Base is a substance which gives hydroxyl ions in aqueous solution.

Answer

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

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

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

Explanation of Solution

In aqueous solution, Water is the solvent which is weekly dissociated as,

$H_{2}O\rightleftharpoons H^{+}+O{H}^{-}$

Thus, if the substance is acid, $\left[H^{+}\right]>\left[O{H}^{-}\right]$

If the substance is base, $\left[H^{+}\right]<\left[O{H}^{-}\right]$

If the substance is neutral, $\left[H^{+}\right]=\left[O{H}^{-}\right]$

Conclusion

Thus,

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

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

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