The dissociation constant of a weak acid is 1.0 × 10-5, the equilibrium constant for the reaction with strong base is

HA   ⇌   H+  +  A-   ;   Ka   =  H+  A-HANeutralization of the weak acid with strong base is HA   +     OH-   ⇌   A-  + H2OK =A-HA  OH-Dividing (i) by (ii),   KaK =  H+   OH-  Given ,  Ka = 10-5K = KaKw =10-510-14  = 109