Chapter 16, Problem 16.35QE

(a)

Interpretation Introduction

Interpretation:

When adding $\text{10}\text{.0 g}$ sodium benzoate to $\text{3}\text{.00 g}$ benzoic acid and dissolving in water in $\text{1}\text{.00 L}$ of solution, pH of the solution has to be calculated.

Concept introduction:

The pH of solution is calculated by using Henderson – Hasselbalch equation,

  $\text{pH = pKa + log }\left(\frac{\left[\text{Base}\right]}{\left[\text{Acid}\right]}\right)$

  ${\text{pK}}_{\text{a}}\text{ = -log}\left[{\text{K}}_{\text{a}}\right]$

A solution may be acidic and basic depends on relative strength of anions as an acid or base. Anions and cations can be acidic, basic and netural. Acidic have $\text{pH < 7}$, basic have $\text{pH > 7}$ and netural have $\text{pH=7}$.

(b)

Interpretation Introduction

Interpretation:

When adding $\text{25}\text{.0 g}$ sodium acetate to $\text{9}\text{.00 g}$ acetic acid and dissolving in water in $\text{500}\text{mL}$ of solution, pH of the solution has to be calculated.

Concept introduction:

Refer to part (a)