Chapter 16, Problem 127AP

Interpretation Introduction

Interpretation:

Among the given solutions, the solution whose pH will be lowered on addition of equal volume of $0.60M\text{NaOH}$ is to be determined.

Concept introduction:

pH of a strong base added to water is determined by its hydronium ion concentration.

$\text{pH}=-\log \left[{\text{H}}_3{\text{O}}^{+}\right]$ …… (1)

The relationship between $\left[{\text{OH}}^{-}\right]\text{ and }\left[{\text{H}}_3{\text{O}}^{+}\right]$ is:

$\left[{\text{H}}_3{\text{O}}^{+}\right]\text{ = }\frac{1.0\times {10}^{-14}}{\left[{\text{OH}}^{-}\right]}$ …… (2)

When a strong acid is neutralized by a strong base, the pH of the solution is determined by the unused moles of either acid or base. These moles are expressed in terms of concentration and the pH is calculated.

When a strong base is added into another strong base, the equivalent concentration of hydroxide ions and hydronium ions are calculated. This is then used to calculate the pH of the solution.