Q.

The specific conductance of 0.0025 M acetic acid is 5×10-5 S cm-1 at a certain temperature. The dissociation constant of acetic acid is ______ ×10-7. Consider limiting molar conductivity of CH3COOH as 400 S cm2 mol-1.                 [2023]


Ans.

(66)

Λm=1000×KC=1000×5×10-50.0025=20 S cm2mol-1

α=20400=120

Ka=Cα21-α2=0.0025×120×1201-120=0.002519×20=66×10-7