Acetic acid, (CH₃COOH), has a pK_a of 4.8. Ethanol, (CH₃CH₂OH), has a pK_a of 16.0. What are the major species present, when acetic acid and ethanol are added to water, and the pH is adjusted to 7.O ?

According to Henderson equation.
$\mathrm{pH}={\mathrm{pK}}_{\mathrm{a}}+\log \frac{\left[\mathrm{salt}\right]}{\left[\text{ Acid }\right]}$
If $\mathrm{pH}>{\mathrm{pK}}_{\mathrm{a}}\Rightarrow \left[\text{ salt }\right]>\left[\text{ acid }\right]$
or Concentration of basic part is more than acidic part while if $\mathrm{pH}<{\mathrm{pK}}_{\mathrm{a}};\text{ (Acidic part) }$> (Basic part).
Thus, for CH₃COOH at pH = 7 ; ${\mathrm{CH}}_3{\mathrm{COO}}^{\ominus }$ exist more (pK_a = 4.8)
& for CH₃CH₂OH at pH = 7 ; CH₃CH₂OH exist more (pK_a = 16)