Chapter 16, Problem 16.43QP

Interpretation Introduction

Interpretation:

The $\text{pH}$ an given $\text{HF}$ solution value is $6.20$ with $\text{HF}$ conjugate base/acid the ratio has to be calculated.

Concept Information:

When a Bronsted acid donates a proton, what remains of the acid is known as a conjugate base; when a Bronsted base accepts a proton, the newly formed protonated species is known as a conjugate acid.  This can be given by the below equation as shown in Figure 1.

Figure 1

Acid ionization constant${\text{K}}_{\text{a}}$:

Acids ionize in water. Strong acids ionize completely whereas weak acids ionize to some limited extent.

The degree to which a weak acid ionizes depends on the concentration of the acid and the equilibrium constant for the ionization.

The ionization of a weak acid $\text{HA}$ can be given as follows,

  ${\text{HA}}_{\text{(aq)}}\to {\text{ H}}^{\text{+}}{}_{\text{(aq)}}{\text{+A}}^{\text{-}}{}_{\text{(aq)}}$

The equilibrium expression for the above reaction is given below.

  ${\text{K}}_{\text{a}}=\frac{[{\text{H}}^{\text{+}}{\text{][A}}^{\text{-}}\text{]}}{[\text{HA]}}$

Where,

  $K_a$ is acid ionization constant,

  $[{\text{H}}^{\text{+}}\text{]}$  is concentration of hydrogen ion

  $[{\text{A}}^{\text{-}}\text{]}$  is concentration of acid anion

  $[\text{HA]}$ is concentration of the acid

$\text{pH}$ definition:

The concentration of hydrogen ion is measured using $\text{pH}$ scale. The acidity of aqueous solution is expressed by $\text{pH}$ scale.

The $\text{pH}$ of a solution is defined as the negative base-10 logarithm of the hydrogen or hydronium ion concentration.

  $\text{pH}\text{=}{\text{-log[H}}^{\text{+}}\text{]}$