[tex]K_a[/tex] = [tex]\dfrac{[H^{+}] [A^{-}]}{[HA]}[/tex]
Explanation:
- When an aqueous solution of a certain acid is prepared it is dissociated is as follows-
[tex]{\displaystyle {\ce {HA[/tex] ⇄ [tex]{H^+}+{A^{-}}} }}[/tex]
Here HA is a protonic acid such as acetic acid, [tex]CH_3COOH[/tex]
- The double arrow signifies that it is an equilibrium process, which means the dissociation and recombination of the acid occur simultaneously.
- The acid dissociation constant can be given by -
[tex]K_a[/tex] = [tex]\dfrac{[H^{+}] [A^{-}]}{[HA]}[/tex]
- The reaction is can also be represented by Bronsted and lowry -
[tex]\\{\displaystyle {\ce {{HA}+ H_2O}[/tex] ⇄ [tex][H_3O^+] [A^-][/tex]
- Then the dissociation constant will be
[tex]K_a[/tex] = [tex]\dfrac{[H_3O^{+}] [A^{-}]}{[HA]}[/tex]
Here, [tex]K_a[/tex] is the dissociation constant of an acid.
