Question

Which percentage is most likely the dissociation constant of a strong acid?
A.0%
B. 0.01 %
C. 50 %
D. 99.99 %

Answer 1

Dissociation is the property of any substance to disperse into its constituent ions. Dissociation constant of any acid is the measurement of the strength of that acid, or the measure of its hydrogen ions, which tells us the strength of any acid. It is denoted by ${{K}_{a}}$.

Complete answer:
A strong acid is the one which liberates more hydrogen ions in the aqueous solution. Since a strong acid completely dissociates into its respective ions, so its dissociation constant percentage will be the highest amount of percentage.
The dissociation of any acid is given by the formula, ${{K}_{a}}=\dfrac{[{{A}^{-}}][{{H}^{+}}]}{[HA]}$ where, A is the conjugate base, H is the hydrogen ions, HA is the acid. As the dissociation will be maximum, so the value of dissociation percent of strong acid will be 99.99 %.
Hence, a strong acid will dissociate with 99.99 %.

So option D is correct.

Additional information:
As given for acids, similarly for bases the ability to liberate more amounts of hydroxide ions decides the strength of bases. More the dissociation of hydroxide ions more is the dissociation of a base. The dissociation constant for a base is denoted by ${{K}_{b}}$.

Note:
Strong acids dissociate completely in the aqueous solution imparting hydrogen ions, while weak acids will have less dissociation in the aqueous solutions so the value percentage of their dissociation constants will also be less.