The conductivity of a weak acid HA of concentration 0.001 ~mol ~L ⁻¹ is 2.0 10⁻⁵ ~S ~cm ⁻¹ . If _ m ^ ( HA )=190 ~S ~cm ^2 ~mol ⁻¹ , the ionization constant ( K _ a ) of HA is equal to _______ x 10⁻⁶ .

Step-by-step solution

_ m =1000 K M =1000 2 10⁻⁵ 0.001 =20 ~S ~cm ^2 ~mol ⁻¹ = _ m _ m ^ = 20 190 = ( 2 19 ) 0.001(1- ) HA 0.001 H ⁺ + 0.001 A ⁻ K_ a =0.001 ( ^2 1- )= 0.001 ( 2 19 )^2 1- ( 2 19 ) =12.3 10⁻⁶