Chapter 18.3, Problem 38SSC

Interpretation Introduction

Interpretation:

The effect on concentration of hydrogen ions is to be discussed when a few drops of $NaOH$ are added to it.

Concept introduction:

Le Chatelier’s principle states that whenever there is a change in temperature, pressure or concentration of a reaction, equilibrium shifts in a direction to nullify the effect.

Answer to Problem 38SSC

Hydrogen ion concentration will decrease.

Explanation of Solution

Acetic acid dissociates as:

$C{H}_{3}COOH\rightleftharpoons H^{+}+C{H}_{3}CO{O}^{-}$

When $NaOH$ is added to it, it dissociates in water as:

$NaOH\to N{a}^{+}+O{H}^{-}$

Thus on adding $NaOH$ concentration of hydrogen ions is decreased as hydroxyl ions react with hydrogen ions to produce water. Therefore, hydrogen ion concentration will decrease.

Conclusion

Due to neutralization reaction, hydrogen ion concentration will decrease.