Given the following molar conductivites at 25∘ C; HCl=426Ω−1 cm2 mol−1; NaCl=126Ω−1 cm2 mol−1, NaCro (sodium crotonate) =83Ω−1 cm2 mol−1. The conductivity of 0.001 mol/dm3 acid solution is 3.83×10−5Ω−1 cm−1. The dissociation constant of crotonic acid is
1.11×10−5M
Λ∘=426−126+83=383
Λ=3.83×10−5×10000.001=38.3
∝=ΛΛ∘=38.3383=0.1;Ka=C∝21−∝=10−3×(0.1)2(1−0.1)=1.11×10−5