In an aqueous solution of a certain acid the acid is 0.10% dissociated and the pH is 4.06. Calculate the acid dissociation constant Ka of the acid. Round your answer to 2 significant digits

Answer : The acid dissociation constant Ka of the acid is,

Explanation :

First we have to calculate the concentration of hydrogen ion.

Given: pH = 4.06

The dissociation of acid reaction is:

Initial conc.      c        0         0

At eqm.           c-cα    cα       cα

Given:

Degree of dissociation = α = 0.10 % = 0.001

The expression of dissociation constant of acid is:

Now put all the given values in this expression, we get:

Thus, the acid dissociation constant Ka of the acid is,