Question

When a aqueous solution of a certain acid is prepared, the acid is dissociated. Calculate the acid dissociation constant of the acid. Round your answer to significant digits.

Answer 1

$K_a$ = $\dfrac{[H^{+}] [A^{-}]}{[HA]}$

Explanation:

• When an aqueous solution of a certain acid is prepared it is dissociated is as follows-

        ${\displaystyle {\ce {HA$  ⇄  ${H^+}+{A^{-}}} }}$

Here HA is a protonic acid such as acetic acid, $CH_3COOH$

• 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 -

        $K_a$ = $\dfrac{[H^{+}] [A^{-}]}{[HA]}$

• The reaction is can also be represented by Bronsted and lowry -

         $\\{\displaystyle {\ce {{HA}+ H_2O}$ ⇄  $[H_3O^+] [A^-]$

• Then the dissociation constant will be

        $K_a$ = $\dfrac{[H_3O^{+}] [A^{-}]}{[HA]}$

Here, $K_a$ is the dissociation constant of an acid.