Chapter 1, Problem 11P

Interpretation Introduction

Interpretation:

The values of ratio of acetate ion to acetic acid and ethylamine to ethylammonium is to be determined.

Concept introduction:

The expression to calculate ${\text{H}}^{+}$ ion concentration is as follows,

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

The expression for the ratio of acetate to acetic acid, which can be done with help of expression of $\text{p}{K}_{\text{a}}$ given below,

$K_{\text{a}}=\frac{\left[{\text{CH}}_3{\text{COO}}^{-}\right]\left[{\text{H}}^{+}\right]}{\left[{\text{CH}}_3\text{COOH}\right]}$ ...... (2)

Where,

• $\left[{\text{CH}}_3{\text{COO}}^{-}\right]$ is the concentration of acetate ion.
• $\left[{\text{CH}}_3\text{COOH}\right]$ is the concentration of acetic acid.
• $\left[{\text{H}}^{+}\right]$ is the concentration of hydrogen ions.
• $K_{\text{a}}$ is equilibrium constant of the acid.

The ratio of ethylamine to ethylammonium is calculated as follows:

$K_{\text{b}}\text{=}\frac{\left[{\text{C}}_2{\text{H}}_5{\text{NH}}_3{}^{+}\right]\left[{\text{OH}}^{-}\right]}{\left[{\text{C}}_2{\text{H}}_5{\text{NH}}_2\right]}$ ...... (3)

Where,

• $K_{\text{b}}$ is the dissociation constant of the base.
• $\left[{\text{C}}_2{\text{H}}_5{\text{NH}}_3{}^{+}\right]$ is the concentration of ethylammonium ion.
• $\left[{\text{OH}}^{-}\right]$ is the concentration of hydroxyl ion.
• $\left[{\text{C}}_2{\text{H}}_5{\text{NH}}_2\right]$ is the concentration of ethylamine.