Question

Enough of a monoprotic acid is dissolved in water to produce a 0.0168 M solution. The pH of the resulting solution is 2.34. Calculate the Ka for the acid.

Answer 1

Answer.plan.first find the[ H+] from p^H given inthe problem.then degree of dissociation ,finally find out K_a by using ostwald's dilution law.

               p^H =- log [ H+]=2.34

         [ H+]=10^-2.34 =10^-3x10^0.66=4.48x10^-3

degree of dissociation = [ H+]/C=4.48x10^-3 /0.0168

                                     =266.67x10^-3

according to ostwald's dilution law ,K_a=C² =0.0168x(266.67x10^-3)² =1194.68x10^-6 =1.19x10^-3

K_a of the monoprotic acid is 1.19x10^-3.